diff --git a/src/cli/dev.ts b/src/cli/dev.ts
index 4fe6ea6fb..421f1bd71 100644
--- a/src/cli/dev.ts
+++ b/src/cli/dev.ts
@@ -86,22 +86,23 @@ export default async function dev() {
 	// TODO watch the configs themselves?
 	const compilers = create_compilers();
 
-	function watch_files(pattern: string, callback: () => void) {
+	function watch_files(pattern: string, events: string[], callback: () => void) {
 		const watcher = chokidar.watch(pattern, {
-			persistent: false
+			persistent: true,
+			ignoreInitial: true
 		});
 
-		watcher.on('add', callback);
-		watcher.on('change', callback);
-		watcher.on('unlink', callback);
+		events.forEach(event => {
+			watcher.on(event, callback);
+		});
 	}
 
-	watch_files('routes/**/*.+(html|js|mjs)', () => {
+	watch_files('routes/**/*', ['add', 'unlink'], () => {
 		const routes = create_routes();
 		create_app({ routes, dev_port });
 	});
 
-	watch_files('app/template.html', () => {
+	watch_files('app/template.html', ['change'], () => {
 		const template = create_template();
 		// TODO reload current page?
 	});
diff --git a/src/core/create_app.ts b/src/core/create_app.ts
index 38a02d19c..79165fff0 100644
--- a/src/core/create_app.ts
+++ b/src/core/create_app.ts
@@ -6,14 +6,28 @@ import { fudge_mtime, posixify, write } from './utils';
 import { dev } from '../config';
 import { Route } from '../interfaces';
 
+// in dev mode, we avoid touching the fs unnecessarily
+let last_client_manifest: string = null;
+let last_server_manifest: string = null;
+
 export default function create_app({ routes, dev_port }: {
 	routes: Route[];
 	dev_port: number;
 }) {
 	mkdirp.sync('app/manifest');
 
-	write('app/manifest/client.js', generate_client(routes, dev_port));
-	write('app/manifest/server.js', generate_server(routes));
+	const client_manifest = generate_client(routes, dev_port);
+	const server_manifest = generate_server(routes);
+
+	if (client_manifest !== last_client_manifest) {
+		write(`app/manifest/client.js`, client_manifest);
+		last_client_manifest = client_manifest;
+	}
+
+	if (server_manifest !== last_server_manifest) {
+		write(`app/manifest/server.js`, server_manifest);
+		last_server_manifest = server_manifest;
+	}
 }
 
 function generate_client(routes: Route[], dev_port?: number) {