diff --git a/app/assets/javascripts/discourse-widget-hbs/index.js b/app/assets/javascripts/discourse-widget-hbs/index.js
index 21fe440d27d..d76f936f732 100644
--- a/app/assets/javascripts/discourse-widget-hbs/index.js
+++ b/app/assets/javascripts/discourse-widget-hbs/index.js
@@ -1,9 +1,6 @@
 "use strict";
 
-const WidgetHbsCompiler =
-  require("../../../../lib/javascripts/widget-hbs-compiler").WidgetHbsCompiler;
-
-const glimmer = require("@glimmer/syntax");
+const widgetHbsCompilerPath = require.resolve("./lib/widget-hbs-compiler");
 
 module.exports = {
   name: require("./package").name,
@@ -15,9 +12,12 @@ module.exports = {
     addonOptions.babel.plugins = addonOptions.babel.plugins || [];
     let babelPlugins = addonOptions.babel.plugins;
 
-    WidgetHbsCompiler.cacheKey = () => "discourse-widget-hbs";
-    WidgetHbsCompiler.glimmer = glimmer;
-    babelPlugins.push(WidgetHbsCompiler);
+    babelPlugins.push({
+      _parallelBabel: {
+        requireFile: widgetHbsCompilerPath,
+        useMethod: "WidgetHbsCompiler",
+      },
+    });
   },
 
   _getAddonOptions() {
diff --git a/lib/javascripts/widget-hbs-compiler.js b/app/assets/javascripts/discourse-widget-hbs/lib/widget-hbs-compiler.js
similarity index 99%
rename from lib/javascripts/widget-hbs-compiler.js
rename to app/assets/javascripts/discourse-widget-hbs/lib/widget-hbs-compiler.js
index 0b70f166950..9efebf16ec6 100644
--- a/lib/javascripts/widget-hbs-compiler.js
+++ b/app/assets/javascripts/discourse-widget-hbs/lib/widget-hbs-compiler.js
@@ -373,4 +373,6 @@ const WidgetHbsCompiler = function (babel) {
   };
 };
 
+WidgetHbsCompiler.cacheKey = () => "discourse-widget-hbs";
+
 exports.WidgetHbsCompiler = WidgetHbsCompiler;
diff --git a/app/assets/javascripts/discourse/ember-cli-build.js b/app/assets/javascripts/discourse/ember-cli-build.js
index 336efc808ca..e273e21ccaa 100644
--- a/app/assets/javascripts/discourse/ember-cli-build.js
+++ b/app/assets/javascripts/discourse/ember-cli-build.js
@@ -10,36 +10,16 @@ const { parsePluginClientSettings } = require("./lib/site-settings-plugin");
 const discourseScss = require("./lib/discourse-scss");
 const generateScriptsTree = require("./lib/scripts");
 const funnel = require("broccoli-funnel");
-
-const SILENCED_WARN_PREFIXES = [
-  "Setting the `jquery-integration` optional feature flag",
-  "The Ember Classic edition has been deprecated",
-  "Setting the `template-only-glimmer-components` optional feature flag to `false`",
-  "DEPRECATION: Invoking the `<LinkTo>` component with positional arguments is deprecated",
-];
+const DeprecationSilencer = require("./lib/deprecation-silencer");
 
 module.exports = function (defaults) {
   let discourseRoot = resolve("../../../..");
   let vendorJs = discourseRoot + "/vendor/assets/javascripts/";
 
-  // Silence the warnings listed in SILENCED_WARN_PREFIXES
+  // Silence deprecations which we are aware of - see `lib/deprecation-silencer.js`
   const ui = defaults.project.ui;
-  const oldWriteWarning = ui.writeWarnLine.bind(ui);
-  ui.writeWarnLine = (message, ...args) => {
-    if (!SILENCED_WARN_PREFIXES.some((prefix) => message.startsWith(prefix))) {
-      return oldWriteWarning(message, ...args);
-    }
-  };
-
-  // Silence warnings which go straight to console.warn (e.g. template compiler deprecations)
-  /* eslint-disable no-console */
-  const oldConsoleWarn = console.warn.bind(console);
-  console.warn = (message, ...args) => {
-    if (!SILENCED_WARN_PREFIXES.some((prefix) => message.startsWith(prefix))) {
-      return oldConsoleWarn(message, ...args);
-    }
-  };
-  /* eslint-enable no-console */
+  DeprecationSilencer.silenceUiWarn(ui);
+  DeprecationSilencer.silenceConsoleWarn();
 
   const isProduction = EmberApp.env().includes("production");
   const isTest = EmberApp.env().includes("test");
@@ -111,6 +91,14 @@ module.exports = function (defaults) {
       ],
     },
 
+    "ember-cli-babel": {
+      throwUnlessParallelizable: true,
+    },
+
+    babel: {
+      plugins: [DeprecationSilencer.generateBabelPlugin()],
+    },
+
     // We need to build tests in prod for theme tests
     tests: true,
 
diff --git a/app/assets/javascripts/discourse/lib/deprecation-silencer.js b/app/assets/javascripts/discourse/lib/deprecation-silencer.js
new file mode 100644
index 00000000000..e6ff2d4107f
--- /dev/null
+++ b/app/assets/javascripts/discourse/lib/deprecation-silencer.js
@@ -0,0 +1,56 @@
+const SILENCED_WARN_PREFIXES = [
+  "Setting the `jquery-integration` optional feature flag",
+  "The Ember Classic edition has been deprecated",
+  "Setting the `template-only-glimmer-components` optional feature flag to `false`",
+  "DEPRECATION: Invoking the `<LinkTo>` component with positional arguments is deprecated",
+];
+
+let consoleWarnSilenced = false;
+
+module.exports = class DeprecationSilencer {
+  static silenceUiWarn(ui) {
+    const oldWriteWarning = ui.writeWarnLine.bind(ui);
+    ui.writeWarnLine = (message, ...args) => {
+      if (
+        !SILENCED_WARN_PREFIXES.some((prefix) => message.startsWith(prefix))
+      ) {
+        return oldWriteWarning(message, ...args);
+      }
+    };
+  }
+
+  static silenceConsoleWarn() {
+    if (consoleWarnSilenced) {
+      return;
+    }
+    /* eslint-disable no-console */
+    const oldConsoleWarn = console.warn.bind(console);
+    console.warn = (message, ...args) => {
+      if (
+        !SILENCED_WARN_PREFIXES.some((prefix) => message.startsWith(prefix))
+      ) {
+        return oldConsoleWarn(message, ...args);
+      }
+    };
+    /* eslint-enable no-console */
+    consoleWarnSilenced = true;
+  }
+
+  /**
+   * Generates a dummy babel plugin which applies the console.warn silences in worker
+   * processes. Does not actually affect babel output.
+   */
+  static generateBabelPlugin() {
+    return {
+      _parallelBabel: {
+        requireFile: require.resolve("./deprecation-silencer"),
+        buildUsing: "babelShim",
+      },
+    };
+  }
+
+  static babelShim() {
+    DeprecationSilencer.silenceConsoleWarn();
+    return {};
+  }
+};
diff --git a/lib/discourse_js_processor.rb b/lib/discourse_js_processor.rb
index f0452f0f1b1..d7bfb8abf42 100644
--- a/lib/discourse_js_processor.rb
+++ b/lib/discourse_js_processor.rb
@@ -172,7 +172,10 @@ class DiscourseJsProcessor
       )
 
       # Widget HBS compiler
-      widget_hbs_compiler_source = File.read("#{Rails.root}/lib/javascripts/widget-hbs-compiler.js")
+      widget_hbs_compiler_source =
+        File.read(
+          "#{Rails.root}/app/assets/javascripts/discourse-widget-hbs/lib/widget-hbs-compiler.js",
+        )
       widget_hbs_compiler_source = <<~JS
         define("widget-hbs-compiler", ["exports"], function(exports){
           #{widget_hbs_compiler_source}