diff --git a/web/app.js b/web/app.js
index 3eab6e6ae..b74ab491a 100644
--- a/web/app.js
+++ b/web/app.js
@@ -155,7 +155,6 @@ const PDFViewerApplication = {
   isViewerEmbedded: window.parent !== window,
   url: "",
   baseUrl: "",
-  _allowedGlobalEventsPromise: null,
   _downloadUrl: "",
   _eventBusAbortController: null,
   _windowAbortController: null,
@@ -175,32 +174,13 @@ const PDFViewerApplication = {
   _printAnnotationStoragePromise: null,
   _touchInfo: null,
   _isCtrlKeyDown: false,
-  _nimbusDataPromise: null,
   _caretBrowsing: null,
   _isScrolling: false,
 
   // Called once when the document is loaded.
   async initialize(appConfig) {
-    let l10nPromise;
-    // In the (various) extension builds, where the locale is set automatically,
-    // initialize the `L10n`-instance as soon as possible.
-    if (typeof PDFJSDev !== "undefined" && !PDFJSDev.test("GENERIC")) {
-      l10nPromise = this.externalServices.createL10n();
-      if (PDFJSDev.test("MOZCENTRAL")) {
-        this._allowedGlobalEventsPromise =
-          this.externalServices.getGlobalEventNames();
-      }
-    }
     this.appConfig = appConfig;
 
-    if (
-      typeof PDFJSDev === "undefined"
-        ? window.isGECKOVIEW
-        : PDFJSDev.test("GECKOVIEW")
-    ) {
-      this._nimbusDataPromise = this.externalServices.getNimbusExperimentData();
-    }
-
     // Ensure that `Preferences`, and indirectly `AppOptions`, have initialized
     // before creating e.g. the various viewer components.
     try {
@@ -229,10 +209,7 @@ const PDFViewerApplication = {
 
     // Ensure that the `L10n`-instance has been initialized before creating
     // e.g. the various viewer components.
-    if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
-      l10nPromise = this.externalServices.createL10n();
-    }
-    this.l10n = await l10nPromise;
+    this.l10n = await this.externalServices.createL10n();
     document.getElementsByTagName("html")[0].dir = this.l10n.getDirection();
     // Connect Fluent, when necessary, and translate what we already have.
     if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) {
@@ -394,11 +371,10 @@ const PDFViewerApplication = {
     let eventBus;
     if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
       eventBus = AppOptions.eventBus = new FirefoxEventBus(
-        await this._allowedGlobalEventsPromise,
+        AppOptions.get("allowedGlobalEvents"),
         externalServices,
         AppOptions.get("isInAutomation")
       );
-      this._allowedGlobalEventsPromise = null;
     } else {
       eventBus = new EventBus();
     }
@@ -564,11 +540,10 @@ const PDFViewerApplication = {
           ? window.isGECKOVIEW
           : PDFJSDev.test("GECKOVIEW")
       ) {
-        this.toolbar = new Toolbar(
-          appConfig.toolbar,
-          eventBus,
-          await this._nimbusDataPromise
+        const nimbusData = JSON.parse(
+          AppOptions.get("nimbusDataStr") || "null"
         );
+        this.toolbar = new Toolbar(appConfig.toolbar, eventBus, nimbusData);
       } else {
         this.toolbar = new Toolbar(
           appConfig.toolbar,
diff --git a/web/app_options.js b/web/app_options.js
index 914bde602..d61aa0bb7 100644
--- a/web/app_options.js
+++ b/web/app_options.js
@@ -56,6 +56,11 @@ const OptionKind = {
  *       primitive types and cannot rely on any imported types.
  */
 const defaultOptions = {
+  allowedGlobalEvents: {
+    /** @type {Object} */
+    value: null,
+    kind: OptionKind.BROWSER,
+  },
   canvasMaxAreaInBytes: {
     /** @type {number} */
     value: -1,
@@ -66,6 +71,16 @@ const defaultOptions = {
     value: false,
     kind: OptionKind.BROWSER,
   },
+  localeProperties: {
+    /** @type {Object} */
+    value: null,
+    kind: OptionKind.BROWSER,
+  },
+  nimbusDataStr: {
+    /** @type {string} */
+    value: "",
+    kind: OptionKind.BROWSER,
+  },
   supportsCaretBrowsingMode: {
     /** @type {boolean} */
     value: false,
diff --git a/web/external_services.js b/web/external_services.js
index 8a3043833..55fbb707d 100644
--- a/web/external_services.js
+++ b/web/external_services.js
@@ -45,12 +45,6 @@ class BaseExternalServices {
     throw new Error("Not implemented: updateEditorStates");
   }
 
-  async getNimbusExperimentData() {}
-
-  async getGlobalEventNames() {
-    return null;
-  }
-
   dispatchGlobalEvent(_event) {}
 }
 
diff --git a/web/firefoxcom.js b/web/firefoxcom.js
index a7cd0068b..63f82397e 100644
--- a/web/firefoxcom.js
+++ b/web/firefoxcom.js
@@ -14,6 +14,7 @@
  */
 
 import { isPdfFile, PDFDataRangeTransport } from "pdfjs-lib";
+import { AppOptions } from "./app_options.js";
 import { BaseExternalServices } from "./external_services.js";
 import { BasePreferences } from "./preferences.js";
 import { DEFAULT_SCALE_VALUE } from "./ui_utils.js";
@@ -396,32 +397,14 @@ class ExternalServices extends BaseExternalServices {
   }
 
   async createL10n() {
-    const [localeProperties] = await Promise.all([
-      FirefoxCom.requestAsync("getLocaleProperties", null),
-      document.l10n.ready,
-    ]);
-    return new L10n(localeProperties, document.l10n);
+    await document.l10n.ready;
+    return new L10n(AppOptions.get("localeProperties"), document.l10n);
   }
 
   createScripting() {
     return FirefoxScripting;
   }
 
-  async getNimbusExperimentData() {
-    if (!PDFJSDev.test("GECKOVIEW")) {
-      return null;
-    }
-    const nimbusData = await FirefoxCom.requestAsync(
-      "getNimbusExperimentData",
-      null
-    );
-    return nimbusData && JSON.parse(nimbusData);
-  }
-
-  async getGlobalEventNames() {
-    return FirefoxCom.requestAsync("getGlobalEventNames", null);
-  }
-
   dispatchGlobalEvent(event) {
     FirefoxCom.request("dispatchGlobalEvent", event);
   }