fix: delay precache for 10s

Checking if CID is already in repo is expensive if the repo itself has a
lot of blocks. This may freeze the Welcome Screen on initial start.

Delaying background precache for 10s is a temporary fix until:
1. we finish async iterators migration
2. implement #878

add-on/src/lib/ipfs-client/index.js

@@ -71,7 +71,7 @@ async function _reloadIpfsClientDependents (instance, opts) {
   // online only
   if (client && instance) {
     // add important data to local ipfs repo for instant load
-    precache(instance)
+    setTimeout(() => precache(instance), 10000)
   }
 }