--- a/browser/components/nsBrowserGlue.js
+++ b/browser/components/nsBrowserGlue.js
@@ -752,21 +752,24 @@ BrowserGlue.prototype = {
                           nb.PRIORITY_WARNING_MEDIUM, buttons);
   },
 
   _notifyDisabledNonMpc() {
     let win = RecentWindow.getMostRecentBrowserWindow();
     if (!win)
       return;
 
-    let message = win.gNavigatorBundle.getString("nonMpcDisabled.message");
+    // This is only going to be on Nightly and only for the 55 and 56
+    // cycles, and it points to a wiki page that is not localized, so
+    // no need to localize the message here...
+    let message = "Due to performance testing, we have disabled some of your add-ons. They can be re-enabled in your browser settings.";
     let buttons = [
       {
-        label: win.gNavigatorBundle.getString("nonMpcDisabled.manage.label"),
-        accessKey: win.gNavigatorBundle.getString("nonMpcDisabled.manage.accessKey"),
+        label: "Manage Add-Ons",
+        accessKey: "M",
         callback() {
           win.BrowserOpenAddonsMgr("addons://list/extension");
         }
       },
     ];
 
     let nb = win.document.getElementById("high-priority-global-notificationbox");
     nb.appendNotification(message, "non-mpc-addons-disabled", "",

--- a/browser/locales/en-US/chrome/browser/browser.properties
+++ b/browser/locales/en-US/chrome/browser/browser.properties
@@ -209,20 +209,16 @@ addonInstallErrorIncompatible=%3$S could
 
 # LOCALIZATION NOTE (addonInstallErrorBlocklisted): %S is add-on name
 addonInstallErrorBlocklisted=%S could not be installed because it has a high risk of causing stability or security problems.
 
 unsignedAddonsDisabled.message=One or more installed add-ons cannot be verified and have been disabled.
 unsignedAddonsDisabled.learnMore.label=Learn More
 unsignedAddonsDisabled.learnMore.accesskey=L
 
-nonMpcDisabled.message=Due to performance testing, we have disabled some of your add-ons. They can be re-enabled in the Add-ons Manager.
-nonMpcDisabled.manage.label=Manage Add-Ons
-nonMpcDisabled.manage.accessKey=M
-
 # LOCALIZATION NOTE (compactLightTheme.name): This is displayed in about:addons -> Appearance
 compactLightTheme.name=Compact Light
 compactLightTheme.description=A compact theme with a light color scheme.
 
 # LOCALIZATION NOTE (compactDarkTheme.name): This is displayed in about:addons -> Appearance
 compactDarkTheme.name=Compact Dark
 compactDarkTheme.description=A compact theme with a dark color scheme.