diff --git a/platform/chromium/vapi-webrequest.js b/platform/chromium/vapi-webrequest.js
index e949b01dd..d999b56b9 100644
--- a/platform/chromium/vapi-webrequest.js
+++ b/platform/chromium/vapi-webrequest.js
@@ -148,3 +148,44 @@
 })();
 
 /******************************************************************************/
+
+// https://github.com/gorhill/uBlock/issues/2067
+//   Experimental: Block everything until uBO is fully ready.
+
+vAPI.net.onBeforeReady = (function() {
+    let pendings;
+
+    const handler = function(details) {
+        if ( pendings === undefined ) { return; }
+        if ( details.tabId < 0 ) { return; }
+
+        pendings.add(details.tabId);
+
+        return { cancel: true };
+    };
+
+    return {
+        experimental: true,
+        start: function() {
+            pendings = new Set();
+            browser.webRequest.onBeforeRequest.addListener(
+                handler,
+                { urls: [ 'http://*/*', 'https://*/*' ] },
+                [ 'blocking' ]
+            );
+        },
+        // https://github.com/gorhill/uBlock/issues/2067
+        //   Force-reload tabs for which network requests were blocked
+        //   during launch. This can happen only if tabs were "suspended".
+        stop: function() {
+            if ( pendings === undefined ) { return; }
+            browser.webRequest.onBeforeRequest.removeListener(handler);
+            for ( const tabId of pendings ) {
+                vAPI.tabs.reload(tabId);
+            }
+            pendings = undefined;
+        },
+    };
+})();
+
+/******************************************************************************/
diff --git a/platform/firefox/vapi-webrequest.js b/platform/firefox/vapi-webrequest.js
index 812c9655b..0ba557708 100644
--- a/platform/firefox/vapi-webrequest.js
+++ b/platform/firefox/vapi-webrequest.js
@@ -130,3 +130,52 @@
 })();
 
 /******************************************************************************/
+
+// Related issues:
+// - https://github.com/gorhill/uBlock/issues/2067
+// - https://github.com/uBlockOrigin/uBlock-issues/issues/128
+// - https://bugzilla.mozilla.org/show_bug.cgi?id=1503721
+
+vAPI.net.onBeforeReady = (function() {
+    let pendings;
+
+    const handler = function(details) {
+        if ( pendings === undefined ) { return; }
+        if ( details.tabId < 0 ) { return; }
+
+        const pending = {
+            details: Object.assign({}, details),
+            resolve: undefined,
+            promise: undefined
+        };
+
+        pending.promise = new Promise(function(resolve) {
+            pending.resolve = resolve;
+        });
+
+        pendings.push(pending);
+
+        return pending.promise;
+    };
+
+    return {
+        start: function() {
+            pendings = [];
+            browser.webRequest.onBeforeRequest.addListener(
+                handler,
+                { urls: [ 'http://*/*', 'https://*/*' ] },
+                [ 'blocking' ]
+            );
+        },
+        stop: function(resolver) {
+            if ( pendings === undefined ) { return; }
+            for ( const pending of pendings ) {
+                const result = resolver(pending.details);
+                pending.resolve(result);
+            }
+            pendings = undefined;
+        },
+    };
+})();
+
+/******************************************************************************/
diff --git a/src/js/start.js b/src/js/start.js
index 827c59b02..ad7ba5e73 100644
--- a/src/js/start.js
+++ b/src/js/start.js
@@ -53,6 +53,8 @@ vAPI.app.onShutdown = function() {
 // - Schedule next update operation.
 
 var onAllReady = function() {
+    µb.webRequest.start();
+
     // Ensure that the resources allocated for decompression purpose (likely
     // large buffers) are garbage-collectable immediately after launch.
     // Otherwise I have observed that it may take quite a while before the
@@ -60,7 +62,6 @@ var onAllReady = function() {
     // as possible ensure minimal memory usage baseline.
     µb.lz4Codec.relinquish();
 
-    µb.webRequest.start();
     initializeTabs();
 
     // https://github.com/chrisaljoudi/uBlock/issues/184
diff --git a/src/js/traffic.js b/src/js/traffic.js
index bf84bd17d..cc211e1be 100644
--- a/src/js/traffic.js
+++ b/src/js/traffic.js
@@ -992,28 +992,17 @@ const strictBlockBypasser = {
 
 return {
     start: (function() {
-        const suspendedTabs = new Set();
-        const onBeforeReady = function(details) {
-            if ( details.type !== 'main_frame' && details.tabId > 0 ) {
-                suspendedTabs.add(details.tabId);
-                console.info('uBO suspend tab %d, block %s', details.tabId, details.url);
-                return { cancel: true };
-            }
-        };
-        // https://github.com/gorhill/uBlock/issues/2067
-        //   Experimental: Block everything until uBO is fully ready.
-        // https://github.com/gorhill/uBlock/issues/3130
-        //   Don't block root frame.
-        if ( µBlock.hiddenSettings.suspendTabsUntilReady ) {
-            vAPI.net.addListener(
-                'onBeforeRequest',
-                onBeforeReady,
-                { urls: [ 'http://*/*', 'https://*/*' ] },
-                [ 'blocking' ]
-            );
+        if (
+            vAPI.net.onBeforeReady instanceof Object &&
+            (
+                vAPI.net.onBeforeReady.experimental !== true ||
+                µBlock.hiddenSettings.suspendTabsUntilReady
+            )
+        ) {
+            vAPI.net.onBeforeReady.start();
         }
+
         return function() {
-            vAPI.net.removeListener('onBeforeRequest', onBeforeReady);
             vAPI.net.addListener(
                 'onBeforeRequest',
                 onBeforeRequest,
@@ -1040,14 +1029,9 @@ return {
                     [ 'blocking', 'requestBody' ]
                 );
             }
-            // https://github.com/gorhill/uBlock/issues/2067
-            //   Force-reload tabs for which network requests were blocked
-            //   during launch. This can happen only if tabs were "suspended".
-            for ( const tabId of suspendedTabs ) {
-                console.info('uBO suspend tab %d, force reload', tabId);
-                vAPI.tabs.reload(tabId);
+            if ( vAPI.net.onBeforeReady instanceof Object ) {
+                vAPI.net.onBeforeReady.stop(onBeforeRequest);
             }
-            suspendedTabs.clear();
         };
     })(),