diff --git a/lib/browser/chrome-extension.js b/lib/browser/chrome-extension.js
index b0045294f38e..835d1b150f5b 100644
--- a/lib/browser/chrome-extension.js
+++ b/lib/browser/chrome-extension.js
@@ -149,10 +149,6 @@ const manifestToExtensionInfo = function (manifest) {
 const loadDevToolsExtensions = function (win, manifests) {
   if (!win.devToolsWebContents) return
 
-  for (const manifest of manifests) {
-    startBackgroundPages(manifest)
-    injectContentScripts(manifest)
-  }
   const extensionInfoArray = manifests.map(manifestToExtensionInfo)
   win.devToolsWebContents.executeJavaScript(`DevToolsAPI.addExtensions(${JSON.stringify(extensionInfoArray)})`)
 }
@@ -182,20 +178,6 @@ app.on('will-quit', function () {
 
 // We can not use protocol or BrowserWindow until app is ready.
 app.once('ready', function () {
-  // Load persisted extensions.
-  loadedExtensionsPath = path.join(app.getPath('userData'), 'DevTools Extensions')
-  try {
-    const loadedExtensions = JSON.parse(fs.readFileSync(loadedExtensionsPath))
-    if (Array.isArray(loadedExtensions)) {
-      // Preheat the manifest cache.
-      for (const srcDirectory of loadedExtensions) {
-        getManifestFromPath(srcDirectory)
-      }
-    }
-  } catch (error) {
-    // Ignore error
-  }
-
   // The chrome-extension: can map a extension URL request to real file path.
   const chromeExtensionHandler = function (request, callback) {
     const parsed = url.parse(request.url)
@@ -227,6 +209,23 @@ app.once('ready', function () {
     }
   })
 
+  // Load persisted extensions.
+  loadedExtensionsPath = path.join(app.getPath('userData'), 'DevTools Extensions')
+  try {
+    const loadedExtensions = JSON.parse(fs.readFileSync(loadedExtensionsPath))
+    if (Array.isArray(loadedExtensions)) {
+      for (const srcDirectory of loadedExtensions) {
+        // Start background pages and set content scripts.
+        const manifest = getManifestFromPath(srcDirectory)
+        startBackgroundPages(manifest)
+        injectContentScripts(manifest)
+      }
+    }
+  } catch (error) {
+    // Ignore error
+  }
+
+  // The public API to add/remove extensions.
   BrowserWindow.addDevToolsExtension = function (srcDirectory) {
     const manifest = getManifestFromPath(srcDirectory)
     if (manifest) {
@@ -245,7 +244,7 @@ app.once('ready', function () {
     delete manifestMap[name]
   }
 
-  // Load persisted extensions when devtools is opened.
+  // Load extensions automatically when devtools is opened.
   const init = BrowserWindow.prototype._init
   BrowserWindow.prototype._init = function () {
     init.call(this)