#399: M1342849

browser/base/content/tabbrowser.xml

@@ -1763,6 +1763,7 @@ let remote = false;
             var aForceNotRemote;
             var aNoReferrer;
             var aUserContextId;
+            var aSkipBackgroundNotify;
             if (arguments.length == 2 &&
                 typeof arguments[1] == "object" &&
                 !(arguments[1] instanceof Ci.nsIURI)) {
@@ -1780,6 +1781,7 @@ let remote = false;
               aForceNotRemote       = params.forceNotRemote;
               aNoReferrer           = params.noReferrer;
               aUserContextId        = params.userContextId;
+              aSkipBackgroundNotify = params.skipBackgroundNotify;
             }
 
             // if we're adding tabs, we're past interrupt mode, ditch the owner
@@ -1794,6 +1796,11 @@ let remote = false;
               t.setAttribute("usercontextid", aUserContextId);
             t.setAttribute("crop", "end");
             t.setAttribute("onerror", "this.removeAttribute('image');");
+
+            if (aSkipBackgroundNotify) {
+              t.setAttribute("skipbackgroundnotify", true);
+            }
+
             t.className = "tabbrowser-tab";
 
             // The new browser should be remote if this is an e10s window and
@@ -5184,10 +5191,10 @@ let remote = false;
                                                  selected.left - scrollRect.left);
           }
 
-          if (!this._animateElement.hasAttribute("notifybgtab")) {
-            this._animateElement.setAttribute("notifybgtab", "true");
+          if (!this._animateElement.hasAttribute("highlight")) {
+            this._animateElement.setAttribute("highlight", "true");
             setTimeout(function (ele) {
-              ele.removeAttribute("notifybgtab");
+              ele.removeAttribute("highlight");
             }, 150, this._animateElement);
           }
         ]]></body>
@@ -5278,7 +5285,7 @@ let remote = false;
           if (tab.getAttribute("selected") == "true") {
             //this._fillTrailingGap();
             this._handleTabSelect();
-          } else {
+          } else if (!tab.hasAttribute("skipbackgroundnotify")) {
             this._notifyBackgroundTab(tab);
           }
 

browser/components/sessionstore/SessionStore.jsm

@@ -2932,6 +2932,7 @@ var SessionStoreInternal = {
                 tabbrowser.addTab("about:blank", {
                   skipAnimation: true,
                   forceNotRemote: true,
+                  skipBackgroundNotify: true,
                 }));
 
       if (winData.tabs[t].pinned)

browser/components/sessionstore/TabAttributes.jsm

@@ -32,7 +32,8 @@ var TabAttributesInternal = {
   // 'muted' should not be accessed directly but handled by using the
   //         tab.linkedBrowser.audioMuted/toggleMuteAudio methods.
   // 'pending' is used internal by sessionstore and managed accordingly.
-  _skipAttrs: new Set(["image", "muted", "pending"]),
+  // 'skipbackgroundnotify' is used to speed up startup time (bug 1342849).
+  _skipAttrs: new Set(["image", "muted", "pending", "skipbackgroundnotify"]),
 
   persist: function (name) {
     if (this._attrs.has(name) || this._skipAttrs.has(name)) {

browser/themes/osx/browser.css

@@ -2645,7 +2645,7 @@ toolbarbutton.chevron > .toolbarbutton-menu-dropmarker {
   transition: 1s background-color ease-out;
 }
 
-.tabbrowser-arrowscrollbox > .scrollbutton-down[notifybgtab] {
+.tabbrowser-arrowscrollbox > .scrollbutton-down[highlight] {
   background-color: Highlight;
   transition: none;
 }