diff --git a/app/browser/api/topSites.js b/app/browser/api/topSites.js
new file mode 100644
index 00000000000..48f3c9ccfce
--- /dev/null
+++ b/app/browser/api/topSites.js
@@ -0,0 +1,151 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+'use strict'
+
+const Immutable = require('immutable')
+const appActions = require('../../../js/actions/appActions')
+const debounce = require('../../../js/lib/debounce')
+const siteUtil = require('../../../js/state/siteUtil')
+const {isSourceAboutUrl} = require('../../../js/lib/appUrlUtil')
+const aboutNewTabMaxEntries = 100
+let appStore
+
+let minCountOfTopSites
+let minAccessOfTopSites
+
+const compareSites = (site1, site2) => {
+  if (!site1 || !site2) return false
+  return site1.get('location') === site2.get('location') &&
+    site1.get('partitionNumber') === site2.get('partitionNumber')
+}
+
+const pinnedTopSites = (state) => {
+  return (state.getIn(['about', 'newtab', 'pinnedTopSites']) || Immutable.List()).setSize(18)
+}
+
+const ignoredTopSites = (state) => {
+  return state.getIn(['about', 'newtab', 'ignoredTopSites']) || Immutable.List()
+}
+
+const isPinned = (state, siteProps) => {
+  return pinnedTopSites(state).filter((site) => compareSites(site, siteProps)).size > 0
+}
+
+const isIgnored = (state, siteProps) => {
+  return ignoredTopSites(state).filter((site) => compareSites(site, siteProps)).size > 0
+}
+
+const sortCountDescending = (left, right) => {
+  const leftCount = left.get('count') || 0
+  const rightCount = right.get('count') || 0
+  if (leftCount < rightCount) {
+    return 1
+  }
+  if (leftCount > rightCount) {
+    return -1
+  }
+  if (left.get('lastAccessedTime') < right.get('lastAccessedTime')) {
+    return 1
+  }
+  if (left.get('lastAccessedTime') > right.get('lastAccessedTime')) {
+    return -1
+  }
+  return 0
+}
+
+const removeDuplicateDomains = (list) => {
+  const siteDomains = new Set()
+  return list.filter((site) => {
+    if (!site.get('location')) {
+      return false
+    }
+    try {
+      const hostname = require('../../common/urlParse')(site.get('location')).hostname
+      if (!siteDomains.has(hostname)) {
+        siteDomains.add(hostname)
+        return true
+      }
+    } catch (e) {
+      console.log('Error parsing hostname: ', e)
+    }
+    return false
+  })
+}
+
+const calculateTopSites = (clearCache) => {
+  if (clearCache) {
+    clearTopSiteCacheData()
+  }
+  startCalculatingTopSiteData()
+}
+
+/**
+ * TopSites are defined by users for the new tab page. Pinned sites are attached to their positions
+ * in the grid, and the non pinned indexes are populated with newly accessed sites
+ */
+const startCalculatingTopSiteData = debounce(() => {
+  if (!appStore) {
+    appStore = require('../../../js/stores/appStore')
+  }
+  const state = appStore.getState()
+  // remove folders; sort by visit count; enforce a max limit
+  const sites = (state.get('sites') ? state.get('sites').toList() : new Immutable.List())
+    .filter((site) => !siteUtil.isFolder(site) &&
+      !siteUtil.isImportedBookmark(site) &&
+      !isSourceAboutUrl(site.get('location')) &&
+      (minCountOfTopSites === undefined || (site.get('count') || 0) >= minCountOfTopSites) &&
+      (minAccessOfTopSites === undefined || (site.get('lastAccessedTime') || 0) >= minAccessOfTopSites))
+    .sort(sortCountDescending)
+    .slice(0, aboutNewTabMaxEntries)
+
+  for (let i = 0; i < sites.size; i++) {
+    const count = sites.getIn([i, 'count']) || 0
+    const access = sites.getIn([i, 'lastAccessedTime']) || 0
+    if (minCountOfTopSites === undefined || count < minCountOfTopSites) {
+      minCountOfTopSites = count
+    }
+    if (minAccessOfTopSites === undefined || access < minAccessOfTopSites) {
+      minAccessOfTopSites = access
+    }
+  }
+
+  // Filter out pinned and ignored sites
+  let unpinnedSites = sites.filter((site) => !(isPinned(state, site) || isIgnored(state, site)))
+  unpinnedSites = removeDuplicateDomains(unpinnedSites)
+
+  // Merge the pinned and unpinned lists together
+  // Pinned items have priority because the position is important
+  let gridSites = pinnedTopSites(state).map((pinnedSite) => {
+    // Fetch latest siteDetail objects from appState.sites using location/partition
+    if (pinnedSite) {
+      const matches = sites.filter((site) => compareSites(site, pinnedSite))
+      if (matches.size > 0) return matches.first()
+    }
+    // Default to unpinned items
+    const firstSite = unpinnedSites.first()
+    unpinnedSites = unpinnedSites.shift()
+    return firstSite
+  })
+
+  // Include up to [aboutNewTabMaxEntries] entries so that folks
+  // can ignore sites and have new items fill those empty spaces
+  if (unpinnedSites.size > 0) {
+    gridSites = gridSites.concat(unpinnedSites)
+  }
+
+  const finalData = gridSites.filter((site) => site != null)
+  appActions.topSiteDataAvailable(finalData)
+}, 5 * 1000)
+
+const clearTopSiteCacheData = () => {
+  minCountOfTopSites = undefined
+  minAccessOfTopSites = undefined
+}
+
+module.exports = {
+  calculateTopSites,
+  clearTopSiteCacheData,
+  aboutNewTabMaxEntries
+}
diff --git a/app/browser/reducers/topSitesReducer.js b/app/browser/reducers/topSitesReducer.js
new file mode 100644
index 00000000000..0f89abc79f5
--- /dev/null
+++ b/app/browser/reducers/topSitesReducer.js
@@ -0,0 +1,19 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+'use strict'
+
+const aboutNewTabState = require('../../common/state/aboutNewTabState')
+const appConstants = require('../../../js/constants/appConstants')
+
+const topSitesReducer = (state, action) => {
+  switch (action.actionType) {
+    case appConstants.APP_TOP_SITE_DATA_AVAILABLE:
+      state = aboutNewTabState.setSites(state, action.topSites)
+      break
+  }
+  return state
+}
+
+module.exports = topSitesReducer
diff --git a/app/common/state/aboutNewTabState.js b/app/common/state/aboutNewTabState.js
index 0328d243782..ea855edaf04 100644
--- a/app/common/state/aboutNewTabState.js
+++ b/app/common/state/aboutNewTabState.js
@@ -2,107 +2,14 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const Immutable = require('immutable')
 const {makeImmutable} = require('./immutableUtil')
-const siteUtil = require('../../../js/state/siteUtil')
-const {isSourceAboutUrl} = require('../../../js/lib/appUrlUtil')
-const aboutNewTabMaxEntries = 100
 
-const compareSites = (site1, site2) => {
-  if (!site1 || !site2) return false
-  return site1.get('location') === site2.get('location') &&
-    site1.get('partitionNumber') === site2.get('partitionNumber')
-}
-const pinnedTopSites = (state) => {
-  return (state.getIn(['about', 'newtab', 'pinnedTopSites']) || Immutable.List()).setSize(18)
-}
-const ignoredTopSites = (state) => {
-  return state.getIn(['about', 'newtab', 'ignoredTopSites']) || Immutable.List()
-}
-const isPinned = (state, siteProps) => {
-  return pinnedTopSites(state).filter((site) => compareSites(site, siteProps)).size > 0
-}
-const isIgnored = (state, siteProps) => {
-  return ignoredTopSites(state).filter((site) => compareSites(site, siteProps)).size > 0
-}
-const sortCountDescending = (left, right) => {
-  const leftCount = left.get('count') || 0
-  const rightCount = right.get('count') || 0
-  if (leftCount < rightCount) {
-    return 1
-  }
-  if (leftCount > rightCount) {
-    return -1
-  }
-  if (left.get('lastAccessedTime') < right.get('lastAccessedTime')) {
-    return 1
-  }
-  if (left.get('lastAccessedTime') > right.get('lastAccessedTime')) {
-    return -1
-  }
-  return 0
-}
-const removeDuplicateDomains = (list) => {
-  const siteDomains = new Set()
-  return list.filter((site) => {
-    if (!site.get('location')) {
-      return false
-    }
-    try {
-      const hostname = require('../urlParse')(site.get('location')).hostname
-      if (!siteDomains.has(hostname)) {
-        siteDomains.add(hostname)
-        return true
-      }
-    } catch (e) {
-      console.log('Error parsing hostname: ', e)
-    }
-    return false
-  })
-}
 /**
  * topSites are defined by users. Pinned sites are attached to their positions
  * in the grid, and the non pinned indexes are populated with newly accessed sites
  */
-const getTopSites = (state) => {
-  // remove folders; sort by visit count; enforce a max limit
-  const sites = (state.get('sites') ? state.get('sites').toList() : new Immutable.List())
-    .filter((site) => !siteUtil.isFolder(site))
-    .filter((site) => !siteUtil.isImportedBookmark(site))
-    .filter((site) => !isSourceAboutUrl(site.get('location')))
-    .sort(sortCountDescending)
-    .slice(0, aboutNewTabMaxEntries)
-
-  // Filter out pinned and ignored sites
-  let unpinnedSites = sites.filter((site) => !(isPinned(state, site) || isIgnored(state, site)))
-  unpinnedSites = removeDuplicateDomains(unpinnedSites)
-
-  // Merge the pinned and unpinned lists together
-  // Pinned items have priority because the position is important
-  let gridSites = pinnedTopSites(state).map((pinnedSite) => {
-    // Fetch latest siteDetail objects from appState.sites using location/partition
-    if (pinnedSite) {
-      const matches = sites.filter((site) => compareSites(site, pinnedSite))
-      if (matches.size > 0) return matches.first()
-    }
-    // Default to unpinned items
-    const firstSite = unpinnedSites.first()
-    unpinnedSites = unpinnedSites.shift()
-    return firstSite
-  })
-
-  // Include up to [aboutNewTabMaxEntries] entries so that folks
-  // can ignore sites and have new items fill those empty spaces
-  if (unpinnedSites.size > 0) {
-    gridSites = gridSites.concat(unpinnedSites)
-  }
-
-  return gridSites.filter((site) => site != null)
-}
 
 const aboutNewTabState = {
-  maxSites: aboutNewTabMaxEntries,
-
   getSites: (state) => {
     return state.getIn(['about', 'newtab', 'sites'])
   },
@@ -117,11 +24,12 @@ const aboutNewTabState = {
     return state.setIn(['about', 'newtab', 'updatedStamp'], new Date().getTime())
   },
 
-  setSites: (state) => {
-    state = makeImmutable(state)
-
-    // return a filtered version of the sites array
-    state = state.setIn(['about', 'newtab', 'sites'], getTopSites(state))
+  setSites: (state, topSites) => {
+    if (!topSites) {
+      return state
+    }
+    topSites = makeImmutable(topSites)
+    state = state.setIn(['about', 'newtab', 'sites'], topSites)
     return state.setIn(['about', 'newtab', 'updatedStamp'], new Date().getTime())
   }
 }
diff --git a/app/renderer/components/frame/frame.js b/app/renderer/components/frame/frame.js
index 292c26f40be..5ad3ef64eff 100644
--- a/app/renderer/components/frame/frame.js
+++ b/app/renderer/components/frame/frame.js
@@ -496,7 +496,11 @@ class Frame extends React.Component {
       if (this.frame.isEmpty()) {
         return
       }
-      if (e.favicons && e.favicons.length > 0) {
+      if (e.favicons &&
+          e.favicons.length > 0 &&
+          // Favicon changes lead to recalculation of top site data so only fire
+          // this when needed.  Some sites update favicons very frequently.
+          e.favicons[0] !== this.frame.get('icon')) {
         imageUtil.getWorkingImageUrl(e.favicons[0], (imageFound) => {
           windowActions.setFavicon(this.frame, imageFound ? e.favicons[0] : null)
         })
@@ -599,7 +603,7 @@ class Frame extends React.Component {
       }
     }
 
-    const loadEnd = (savePage, url) => {
+    const loadEnd = (savePage, url, inPageNav) => {
       if (this.frame.isEmpty()) {
         return
       }
@@ -614,7 +618,7 @@ class Frame extends React.Component {
 
       const protocol = parsedUrl.protocol
       const isError = this.props.aboutDetailsErrorCode
-      if (!this.props.isPrivate && (protocol === 'http:' || protocol === 'https:') && !isError && savePage) {
+      if (!this.props.isPrivate && (protocol === 'http:' || protocol === 'https:') && !isError && savePage && !inPageNav) {
         // Register the site for recent history for navigation bar
         // calling with setTimeout is an ugly hack for a race condition
         // with setTitle. We either need to delay this call until the title is
@@ -732,18 +736,18 @@ class Frame extends React.Component {
     }, { passive: true })
     this.webview.addEventListener('did-fail-provisional-load', (e) => {
       if (e.isMainFrame) {
-        loadEnd(false, e.validatedURL)
+        loadEnd(false, e.validatedURL, false)
         loadFail(e, true, e.currentURL)
       }
     })
     this.webview.addEventListener('did-fail-load', (e) => {
       if (e.isMainFrame) {
-        loadEnd(false, e.validatedURL)
+        loadEnd(false, e.validatedURL, false)
         loadFail(e, false, e.validatedURL)
       }
     })
     this.webview.addEventListener('did-finish-load', (e) => {
-      loadEnd(true, e.validatedURL)
+      loadEnd(true, e.validatedURL, false)
       if (this.props.runInsecureContent) {
         appActions.removeSiteSetting(this.props.origin, 'runInsecureContent', this.props.isPrivate)
       }
@@ -754,7 +758,7 @@ class Frame extends React.Component {
       }
       if (e.isMainFrame) {
         windowActions.setNavigated(e.url, this.props.frameKey, true, this.props.tabId)
-        loadEnd(true, e.url)
+        loadEnd(true, e.url, true)
       }
     })
     this.webview.addEventListener('enter-html-full-screen', () => {
diff --git a/js/actions/appActions.js b/js/actions/appActions.js
index e4b0b571bb5..1856b1dca82 100644
--- a/js/actions/appActions.js
+++ b/js/actions/appActions.js
@@ -124,6 +124,13 @@ const appActions = {
     })
   },
 
+  topSiteDataAvailable: function (topSites) {
+    dispatch({
+      actionType: appConstants.APP_TOP_SITE_DATA_AVAILABLE,
+      topSites
+    })
+  },
+
   /**
    * A request for a URL load
    * @param {number} tabId - the tab ID to load the URL inside of
diff --git a/js/constants/appConstants.js b/js/constants/appConstants.js
index 809d8563596..f8e12793899 100644
--- a/js/constants/appConstants.js
+++ b/js/constants/appConstants.js
@@ -1,6 +1,5 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file, * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 const mapValuesByKeys = require('../lib/functional').mapValuesByKeys
 
@@ -107,6 +106,7 @@ const appConstants = {
   APP_TAB_MESSAGE_BOX_UPDATED: _,
   APP_NAVIGATOR_HANDLER_REGISTERED: _,
   APP_NAVIGATOR_HANDLER_UNREGISTERED: _,
+  APP_TOP_SITE_DATA_AVAILABLE: _,
   APP_URL_BAR_TEXT_CHANGED: _,
   APP_URL_BAR_SUGGESTIONS_CHANGED: _,
   APP_SEARCH_SUGGESTION_RESULTS_AVAILABLE: _,
diff --git a/js/stores/appStore.js b/js/stores/appStore.js
index 63fd8cc15aa..9d2096f74e4 100644
--- a/js/stores/appStore.js
+++ b/js/stores/appStore.js
@@ -32,6 +32,7 @@ const nativeImage = require('../../app/nativeImage')
 const filtering = require('../../app/filtering')
 const basicAuth = require('../../app/browser/basicAuth')
 const webtorrent = require('../../app/browser/webtorrent')
+const {calculateTopSites} = require('../../app/browser/api/topSites')
 const assert = require('assert')
 const profiles = require('../../app/browser/profiles')
 const {zoomLevel} = require('../../app/common/constants/toolbarUserInterfaceScale')
@@ -406,6 +407,7 @@ const handleAppAction = (action) => {
       require('../../app/browser/reducers/extensionsReducer'),
       require('../../app/browser/reducers/shareReducer'),
       require('../../app/browser/reducers/updatesReducer'),
+      require('../../app/browser/reducers/topSitesReducer'),
       require('../../app/ledger').doAction,
       require('../../app/browser/menu')
     ]
@@ -443,7 +445,7 @@ const handleAppAction = (action) => {
     case appConstants.APP_CHANGE_NEW_TAB_DETAIL:
       appState = aboutNewTabState.mergeDetails(appState, action)
       if (action.refresh) {
-        appState = aboutNewTabState.setSites(appState, action)
+        calculateTopSites(true)
       }
       break
     case appConstants.APP_POPULATE_HISTORY:
@@ -456,7 +458,7 @@ const handleAppAction = (action) => {
     case appConstants.APP_ADD_BOOKMARK:
     case appConstants.APP_EDIT_BOOKMARK:
       const oldSiteSize = appState.get('sites').size
-      appState = aboutNewTabState.setSites(appState, action)
+      calculateTopSites(false)
       appState = aboutHistoryState.setHistory(appState, action)
       // If there was an item added then clear out the old history entries
       if (oldSiteSize !== appState.get('sites').size) {
@@ -465,7 +467,7 @@ const handleAppAction = (action) => {
       break
     case appConstants.APP_APPLY_SITE_RECORDS:
     case appConstants.APP_REMOVE_SITE:
-      appState = aboutNewTabState.setSites(appState, action)
+      calculateTopSites(true)
       appState = aboutHistoryState.setHistory(appState, action)
       break
     case appConstants.APP_SET_DATA_FILE_ETAG:
@@ -660,7 +662,7 @@ const handleAppAction = (action) => {
       const clearData = defaults ? defaults.merge(temp) : temp
 
       if (clearData.get('browserHistory')) {
-        appState = aboutNewTabState.setSites(appState)
+        calculateTopSites(true)
         appState = aboutHistoryState.setHistory(appState)
         syncActions.clearHistory()
         BrowserWindow.getAllWindows().forEach((wnd) => wnd.webContents.send(messages.CLEAR_CLOSED_FRAMES))
@@ -796,7 +798,9 @@ const handleAppAction = (action) => {
       break
     case windowConstants.WINDOW_SET_FAVICON:
       appState = siteUtil.updateSiteFavicon(appState, action.frameProps.get('location'), action.favicon)
-      appState = aboutNewTabState.setSites(appState, action)
+      if (action.frameProps.get('favicon') !== action.favicon) {
+        calculateTopSites(false)
+      }
       break
     case appConstants.APP_RENDER_URL_TO_PDF:
       const pdf = require('../../app/pdf')
diff --git a/test/unit/app/browser/api/topSitesTest.js b/test/unit/app/browser/api/topSitesTest.js
new file mode 100644
index 00000000000..451f5dd879b
--- /dev/null
+++ b/test/unit/app/browser/api/topSitesTest.js
@@ -0,0 +1,192 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* global describe, it, after, afterEach, before */
+const Immutable = require('immutable')
+const assert = require('assert')
+const siteTags = require('../../../../../js/constants/siteTags')
+const sinon = require('sinon')
+const mockery = require('mockery')
+
+let getStateValue
+
+const defaultAppState = Immutable.fromJS({
+  about: {
+    newtab: {
+      gridLayoutSize: 'large',
+      sites: [],
+      ignoredTopSites: [],
+      pinnedTopSites: [],
+      updatedStamp: undefined
+    }
+  }
+})
+
+const calculateTopSitesClockTime = 1000000
+
+describe('topSites api', function () {
+  before(function () {
+    this.clock = sinon.useFakeTimers()
+    mockery.enable({
+      warnOnReplace: false,
+      warnOnUnregistered: false,
+      useCleanCache: true
+    })
+    mockery.registerMock('electron', require('../../../lib/fakeElectron'))
+    mockery.registerMock('ad-block', require('../../../lib/fakeAdBlock'))
+    this.appActions = require('../../../../../js/actions/appActions')
+    this.appStore = require('../../../../../js/stores/appStore')
+    sinon.stub(this.appActions, 'topSiteDataAvailable')
+    getStateValue = Immutable.Map()
+    sinon.stub(this.appStore, 'getState', () => {
+      return getStateValue
+    })
+    this.topSites = require('../../../../../app/browser/api/topSites')
+  })
+  after(function () {
+    this.appActions.topSiteDataAvailable.restore()
+    this.clock.restore()
+    mockery.disable()
+  })
+  afterEach(function () {
+    this.appActions.topSiteDataAvailable.reset()
+  })
+  describe('calculateTopSites', function () {
+    const site1 = Immutable.fromJS({
+      location: 'https://example1.com/', title: 'sample 1', parentFolderId: 0, count: 10
+    })
+    const site2 = Immutable.fromJS({
+      location: 'https://example2.com', title: 'sample 2', parentFolderId: 0, count: 5
+    })
+    const site3 = Immutable.fromJS({
+      location: 'https://example3.com', title: 'sample 3', parentFolderId: 0, count: 23, lastAccessedTime: 123
+    })
+    const site4 = Immutable.fromJS({
+      location: 'https://example4.com', title: 'sample 4', parentFolderId: 0, count: 0
+    })
+    const site5 = Immutable.fromJS({
+      location: 'https://example4.com', title: 'sample 5', parentFolderId: 0, count: 23, lastAccessedTime: 456
+    })
+    const importedBookmark1 = Immutable.fromJS({
+      location: 'https://example6.com', title: 'sample 6', parentFolderId: 0, count: 23, lastAccessedTime: 0
+    })
+    const folder1 = Immutable.fromJS({
+      customTitle: 'folder1', parentFolderId: 0, tags: [siteTags.BOOKMARK_FOLDER]
+    })
+
+    describe('when fetching unpinned results', function () {
+      it('does not include bookmark folders', function () {
+        const stateWithSites = defaultAppState.set('sites',
+          Immutable.List().push(site1).push(folder1))
+        const expectedSites = Immutable.List().push(site1)
+        getStateValue = stateWithSites
+        this.topSites.calculateTopSites(true)
+        this.clock.tick(calculateTopSitesClockTime)
+        assert.equal(this.appActions.topSiteDataAvailable.callCount, 1)
+        const newSitesData = this.appActions.topSiteDataAvailable.getCall(0).args[0]
+        assert.deepEqual(newSitesData.toJS(), expectedSites.toJS())
+      })
+
+      it('does not include imported bookmarks (lastAccessedTime === 0)', function () {
+        const stateWithSites = defaultAppState.set('sites',
+          Immutable.List().push(site1).push(importedBookmark1))
+        const expectedSites = Immutable.List().push(site1)
+        this.topSites.calculateTopSites(stateWithSites)
+        getStateValue = stateWithSites
+        this.clock.tick(calculateTopSitesClockTime)
+        assert.equal(this.appActions.topSiteDataAvailable.callCount, 1)
+        const newSitesData = this.appActions.topSiteDataAvailable.getCall(0).args[0]
+        assert.deepEqual(newSitesData.toJS(), expectedSites.toJS())
+      })
+
+      it('sorts results by `count` DESC', function () {
+        const stateWithSites = defaultAppState.set('sites',
+          Immutable.List().push(site1).push(site2).push(site3).push(site4))
+        const expectedSites = Immutable.List().push(site3).push(site1).push(site2).push(site4)
+        this.topSites.calculateTopSites(stateWithSites)
+        getStateValue = stateWithSites
+        this.clock.tick(calculateTopSitesClockTime)
+        assert.equal(this.appActions.topSiteDataAvailable.callCount, 1)
+        const newSitesData = this.appActions.topSiteDataAvailable.getCall(0).args[0]
+        assert.deepEqual(newSitesData.toJS(), expectedSites.toJS())
+      })
+
+      it('sorts results by `lastAccessedTime` DESC if `count` is the same', function () {
+        const stateWithSites = defaultAppState.set('sites',
+          Immutable.List().push(site1).push(site3).push(site5))
+        const expectedSites = Immutable.List().push(site5).push(site3).push(site1)
+        this.topSites.calculateTopSites(stateWithSites)
+        getStateValue = stateWithSites
+        this.clock.tick(calculateTopSitesClockTime)
+        assert.equal(this.appActions.topSiteDataAvailable.callCount, 1)
+        const newSitesData = this.appActions.topSiteDataAvailable.getCall(0).args[0]
+        assert.deepEqual(newSitesData.toJS(), expectedSites.toJS())
+      })
+
+      it('only returns the last `maxSites` results', function () {
+        const maxSites = this.topSites.aboutNewTabMaxEntries
+        let tooManySites = Immutable.List()
+        for (let i = 0; i < maxSites + 1; i++) {
+          tooManySites = tooManySites.push(
+            site1.set('location', 'https://example' + i + '.com')
+              .set('title', 'sample ' + i)
+              .set('count', i))
+        }
+        const stateWithTooManySites = defaultAppState.set('sites', tooManySites)
+        this.topSites.calculateTopSites(stateWithTooManySites)
+
+        getStateValue = stateWithTooManySites
+        this.clock.tick(calculateTopSitesClockTime)
+        assert.equal(this.appActions.topSiteDataAvailable.callCount, 1)
+        const newSitesData = this.appActions.topSiteDataAvailable.getCall(0).args[0]
+        assert.equal(newSitesData.size, maxSites)
+        assert.equal(newSitesData.getIn([0, 'title']), 'sample ' + this.topSites.aboutNewTabMaxEntries)
+      })
+
+      it('does not include items marked as ignored', function () {
+        const ignoredSites = Immutable.List().push(site1).push(site3)
+        const stateWithIgnoredSites = defaultAppState
+          .set('sites', Immutable.List().push(site1).push(site2).push(site3).push(site4))
+          .setIn(['about', 'newtab', 'ignoredTopSites'], ignoredSites)
+        const expectedSites = Immutable.List().push(site2).push(site4)
+        this.topSites.calculateTopSites(stateWithIgnoredSites)
+        getStateValue = stateWithIgnoredSites
+        this.clock.tick(calculateTopSitesClockTime)
+        assert.equal(this.appActions.topSiteDataAvailable.callCount, 1)
+        const newSitesData = this.appActions.topSiteDataAvailable.getCall(0).args[0]
+        assert.deepEqual(newSitesData.toJS(), expectedSites.toJS())
+      })
+    })
+
+    it('respects position of pinned items when populating results', function () {
+      const allPinned = Immutable.fromJS([null, null, site1, null, null, null, null, null, site4])
+      const stateWithPinnedSites = defaultAppState
+        .set('sites', Immutable.List().push(site1).push(site2).push(site3).push(folder1).push(site4))
+        .setIn(['about', 'newtab', 'pinnedTopSites'], allPinned)
+      const expectedSites = Immutable.List().push(site3).push(site2).push(site1).push(site4)
+      this.topSites.calculateTopSites(stateWithPinnedSites)
+      // checks:
+      // - pinned item are in their expected order
+      // - unpinned items fill the rest of the spots (starting w/ highest # visits first)
+      getStateValue = stateWithPinnedSites
+      this.clock.tick(calculateTopSitesClockTime)
+      assert.equal(this.appActions.topSiteDataAvailable.callCount, 1)
+      const newSitesData = this.appActions.topSiteDataAvailable.getCall(0).args[0]
+      assert.deepEqual(newSitesData.toJS(), expectedSites.toJS())
+    })
+
+    it('only includes one result for a domain (the one with the highest count)', function () {
+      const stateWithDuplicateDomains = defaultAppState.set('sites', Immutable.List()
+        .push(site1.set('location', 'https://example1.com/test').set('count', 12))
+        .push(site1.set('location', 'https://example1.com/about').set('count', 7)))
+      const expectedSites = Immutable.List().push(site1.set('location', 'https://example1.com/test').set('count', 12))
+      this.topSites.calculateTopSites(stateWithDuplicateDomains)
+      getStateValue = stateWithDuplicateDomains
+      this.clock.tick(calculateTopSitesClockTime)
+      assert.equal(this.appActions.topSiteDataAvailable.callCount, 1)
+      const newSitesData = this.appActions.topSiteDataAvailable.getCall(0).args[0]
+      assert.deepEqual(newSitesData.toJS(), expectedSites.toJS())
+    })
+  })
+})
diff --git a/test/unit/app/browser/reducers/topSitesReducerTest.js b/test/unit/app/browser/reducers/topSitesReducerTest.js
new file mode 100644
index 00000000000..89b783f837e
--- /dev/null
+++ b/test/unit/app/browser/reducers/topSitesReducerTest.js
@@ -0,0 +1,46 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* global describe, it, before, after, afterEach */
+
+const sinon = require('sinon')
+const Immutable = require('immutable')
+const assert = require('assert')
+
+const appConstants = require('../../../../../js/constants/appConstants')
+require('../../../braveUnit')
+
+describe('topSitesReducerTest', function () {
+  let topSitesReducer
+  let setSitesStub
+  before(function () {
+    const aboutNewTabState = require('../../../../../app/common/state/aboutNewTabState')
+    setSitesStub = sinon.stub(aboutNewTabState, 'setSites')
+    topSitesReducer = require('../../../../../app/browser/reducers/topSitesReducer')
+  })
+
+  after(function () {
+    setSitesStub.restore()
+  })
+
+  afterEach(function () {
+    setSitesStub.reset()
+  })
+
+  describe('APP_TOP_SITE_DATA_AVAILABLE', function () {
+    it('sets the data in new tab state', () => {
+      const site1 = Immutable.fromJS({
+        location: 'https://example1.com', title: 'sample 1', parentFolderId: 0, count: 23, lastAccessedTime: 123
+      })
+      const site2 = Immutable.fromJS({
+        location: 'https://example2.com', title: 'sample 2', parentFolderId: 0, count: 0
+      })
+      const topSites = Immutable.fromJS([site1, site2])
+      this.newState = topSitesReducer(Immutable.Map(), {actionType: appConstants.APP_TOP_SITE_DATA_AVAILABLE, topSites})
+      assert.equal(setSitesStub.calledOnce, true)
+      assert.deepEqual(setSitesStub.getCall(0).args[0].toJS(), {})
+      assert.deepEqual(setSitesStub.getCall(0).args[1].toJS(), topSites.toJS())
+    })
+  })
+})
diff --git a/test/unit/app/common/state/aboutNewTabStateTest.js b/test/unit/app/common/state/aboutNewTabStateTest.js
index c40351e9aa0..83a23f46ede 100644
--- a/test/unit/app/common/state/aboutNewTabStateTest.js
+++ b/test/unit/app/common/state/aboutNewTabStateTest.js
@@ -2,7 +2,6 @@
 const aboutNewTabState = require('../../../../../app/common/state/aboutNewTabState')
 const Immutable = require('immutable')
 const assert = require('assert')
-const siteTags = require('../../../../../js/constants/siteTags')
 
 const defaultAppState = Immutable.fromJS({
   about: {
@@ -50,99 +49,22 @@ describe('aboutNewTabState', function () {
     const site3 = Immutable.fromJS({
       location: 'https://example3.com', title: 'sample 3', parentFolderId: 0, count: 23, lastAccessedTime: 123
     })
-    const site4 = Immutable.fromJS({
-      location: 'https://example4.com', title: 'sample 4', parentFolderId: 0, count: 0
-    })
-    const site5 = Immutable.fromJS({
-      location: 'https://example4.com', title: 'sample 5', parentFolderId: 0, count: 23, lastAccessedTime: 456
-    })
-    const importedBookmark1 = Immutable.fromJS({
-      location: 'https://example6.com', title: 'sample 6', parentFolderId: 0, count: 23, lastAccessedTime: 0
-    })
-    const folder1 = Immutable.fromJS({
-      customTitle: 'folder1', parentFolderId: 0, tags: [siteTags.BOOKMARK_FOLDER]
-    })
-
-    describe('when fetching unpinned results', function () {
-      it('does not include bookmark folders', function () {
-        const stateWithSites = defaultAppState.set('sites',
-          Immutable.List().push(site1).push(folder1))
-        const expectedSites = Immutable.List().push(site1)
-        const actualState = aboutNewTabState.setSites(stateWithSites)
-        assert.deepEqual(actualState.getIn(['about', 'newtab', 'sites']).toJS(), expectedSites.toJS())
-      })
-
-      it('does not include imported bookmarks (lastAccessedTime === 0)', function () {
-        const stateWithSites = defaultAppState.set('sites',
-          Immutable.List().push(site1).push(importedBookmark1))
-        const expectedSites = Immutable.List().push(site1)
-        const actualState = aboutNewTabState.setSites(stateWithSites)
-        assert.deepEqual(actualState.getIn(['about', 'newtab', 'sites']).toJS(), expectedSites.toJS())
-      })
-
-      it('sorts results by `count` DESC', function () {
-        const stateWithSites = defaultAppState.set('sites',
-          Immutable.List().push(site1).push(site2).push(site3).push(site4))
-        const expectedSites = Immutable.List().push(site3).push(site1).push(site2).push(site4)
-        const actualState = aboutNewTabState.setSites(stateWithSites)
-        assert.deepEqual(actualState.getIn(['about', 'newtab', 'sites']).toJS(), expectedSites.toJS())
-      })
-
-      it('sorts results by `lastAccessedTime` DESC if `count` is the same', function () {
-        const stateWithSites = defaultAppState.set('sites',
-          Immutable.List().push(site1).push(site3).push(site5))
-        const expectedSites = Immutable.List().push(site5).push(site3).push(site1)
-        const actualState = aboutNewTabState.setSites(stateWithSites)
-        assert.deepEqual(actualState.getIn(['about', 'newtab', 'sites']).toJS(), expectedSites.toJS())
-      })
-
-      it('only returns the last `maxSites` results', function () {
-        const maxSites = aboutNewTabState.maxSites
-        let tooManySites = Immutable.List()
-        for (let i = 0; i < maxSites + 1; i++) {
-          tooManySites = tooManySites.push(
-            site1.set('location', 'https://example' + i + '.com')
-              .set('title', 'sample ' + i)
-              .set('count', i))
-        }
-        const stateWithTooManySites = defaultAppState.set('sites', tooManySites)
-        const actualState = aboutNewTabState.setSites(stateWithTooManySites)
-        const actualSites = actualState.getIn(['about', 'newtab', 'sites'])
-        assert.equal(actualSites.size, maxSites)
-        assert.equal(actualSites.getIn([0, 'title']), 'sample ' + aboutNewTabState.maxSites)
-      })
-
-      it('does not include items marked as ignored', function () {
-        const ignoredSites = Immutable.List().push(site1).push(site3)
-        const stateWithIgnoredSites = defaultAppState
-          .set('sites', Immutable.List().push(site1).push(site2).push(site3).push(site4))
-          .setIn(['about', 'newtab', 'ignoredTopSites'], ignoredSites)
-        const expectedState = Immutable.List().push(site2).push(site4)
-        const actualState = aboutNewTabState.setSites(stateWithIgnoredSites)
-        assert.deepEqual(actualState.getIn(['about', 'newtab', 'sites']).toJS(), expectedState.toJS())
-      })
+    it('updates the `updatedStamp` value on success', function () {
+      const topSites = Immutable.fromJS([site1, site2, site3])
+      const state = aboutNewTabState.setSites(defaultAppState, topSites)
+      assertTimeUpdated(state)
     })
 
-    it('respects position of pinned items when populating results', function () {
-      const allPinned = Immutable.fromJS([null, null, site1, null, null, null, null, null, site4])
-      const stateWithPinnedSites = defaultAppState
-        .set('sites', Immutable.List().push(site1).push(site2).push(site3).push(folder1).push(site4))
-        .setIn(['about', 'newtab', 'pinnedTopSites'], allPinned)
-      const expectedSites = Immutable.List().push(site3).push(site2).push(site1).push(site4)
-      const actualState = aboutNewTabState.setSites(stateWithPinnedSites)
-      // checks:
-      // - pinned item are in their expected order
-      // - unpinned items fill the rest of the spots (starting w/ highest # visits first)
-      assert.deepEqual(actualState.getIn(['about', 'newtab', 'sites']).toJS(), expectedSites.toJS())
+    it('does not update state or `updatedStamp` if input is falsey', function () {
+      const state = aboutNewTabState.setSites(defaultAppState, null)
+      assertNoChange(state)
     })
 
-    it('only includes one result for a domain (the one with the highest count)', function () {
-      const stateWithDuplicateDomains = defaultAppState.set('sites', Immutable.List()
-        .push(site1.set('location', 'https://example1.com/test').set('count', 12))
-        .push(site1.set('location', 'https://example1.com/about').set('count', 7)))
-      const expectedSites = Immutable.List().push(site1.set('location', 'https://example1.com/test').set('count', 12))
-      const actualState = aboutNewTabState.setSites(stateWithDuplicateDomains)
-      assert.deepEqual(actualState.getIn(['about', 'newtab', 'sites']).toJS(), expectedSites.toJS())
+    it('sets the provided data for top sites', function () {
+      const topSites = Immutable.fromJS([site1, site2, site3])
+      const state = aboutNewTabState.setSites(defaultAppState, topSites)
+      const updatedValue = state.getIn(['about', 'newtab', 'sites'])
+      assert.deepEqual(updatedValue.toJS(), topSites.toJS())
     })
   })