--- a/devtools/bootstrap.js
+++ b/devtools/bootstrap.js
@@ -5,20 +5,16 @@
 /* global content, APP_SHUTDOWN */
 /* exported startup, shutdown, install, uninstall */
 
 "use strict";
 
 const Cu = Components.utils;
 const {Services} = Cu.import("resource://gre/modules/Services.jsm", {});
 
-XPCOMUtils.defineLazyGetter(this, "DevToolsPreferences", function () {
-  return Cu.import("chrome://devtools/content/preferences/DevToolsPreferences.jsm", {}).DevToolsPreferences;
-});
-
 function unload(reason) {
   // This frame script is going to be executed in all processes:
   // parent and child
   Services.ppmm.loadProcessScript("data:,(" + function (scriptReason) {
     /* Flush message manager cached frame scripts as well as chrome locales */
     let obs = Components.classes["@mozilla.org/observer-service;1"]
                         .getService(Components.interfaces.nsIObserverService);
     obs.notifyObservers(null, "message-manager-flush-caches");
@@ -45,20 +41,17 @@ function unload(reason) {
   Cu.unload("resource://devtools/shared/Parser.jsm");
   Cu.unload("resource://devtools/client/shared/DOMHelpers.jsm");
   Cu.unload("resource://devtools/client/shared/widgets/VariablesView.jsm");
   Cu.unload("resource://devtools/client/responsivedesign/responsivedesign.jsm");
   Cu.unload("resource://devtools/client/shared/widgets/AbstractTreeItem.jsm");
   Cu.unload("resource://devtools/shared/deprecated-sync-thenables.js");
 }
 
-function startup(data) {
-  // Load DevToolsPreferences as early as possible.
-  DevToolsPreferences.loadPrefs();
-}
+function startup(data) {}
 
 function shutdown(data, reason) {
   // On browser shutdown, do not try to cleanup anything
   if (reason == APP_SHUTDOWN) {
     return;
   }
 
   unload("disable");

--- a/devtools/shared/Loader.jsm
+++ b/devtools/shared/Loader.jsm
@@ -11,16 +11,31 @@
 var { utils: Cu } = Components;
 var { Services } = Cu.import("resource://gre/modules/Services.jsm", {});
 var { Loader, descriptor, resolveURI } = Cu.import("resource://gre/modules/commonjs/toolkit/loader.js", {});
 var { requireRawId } = Cu.import("resource://devtools/shared/loader-plugin-raw.jsm", {});
 
 this.EXPORTED_SYMBOLS = ["DevToolsLoader", "devtools", "BuiltinProvider",
                          "require", "loader"];
 
+// Fire an event to notify the DevTools addon bootstrap that DevTools are being
+// initialized. The loader is always the first entry point for all DevTools consumers.
+Services.obs.notifyObservers(null, "devtools-loader-starting");
+
+// Load DevToolsPreferences as soon as DevTools code starts being required.
+// With DevTools as an addon, the DevTools preferences need to be dynamically loaded.
+const isParentProcess =
+    Services.appinfo.processType === Services.appinfo.PROCESS_TYPE_DEFAULT;
+const isFirefox = Services.appinfo.ID == "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}";
+if (isParentProcess && isFirefox) {
+  // Load client preferences if we are in Firefox's parent process only.
+  const {DevToolsPreferences} =
+    Cu.import("chrome://devtools/content/preferences/DevToolsPreferences.jsm", {});
+  DevToolsPreferences.loadPrefs();
+}
 /**
  * Providers are different strategies for loading the devtools.
  */
 
 /**
  * Used when the tools should be loaded from the Firefox package itself.
  * This is the default case.
  */