Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b7pre) Gecko/20100928 Firefox/4.0b7pre ID:20100928041914 Highlight of hovering bookmarks is lagged while Playing Flash movie. I think that this lag is abnormal. Similar but different from Bug 597338. Reproducible: Always Steps to Reproduce: 1. Start Minefield with new profile 2. Open URL ( http://www.youtube.com/watch?v=K7l0a2PVhPQ&feature=player_embedded ) 3. Open "Latest Headlines" in Bookmarks Toolbar 4. Mouse Hover bookmark items Actual Results: Highlight of hovering bookmarks is lagged. Expected Results: Highlight of hovering bookmarks should be immediately. Regression window: Works: http://hg.mozilla.org/mozilla-central/rev/01fa971e62ee Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5pre) Gecko/20100827 Firefox/4.0b5pre ID:20100827190212 Fails: http://hg.mozilla.org/mozilla-central/rev/0886ad6e6aaa Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5pre) Gecko/20100827 Firefox/4.0b5pre ID:20100827190555 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=01fa971e62ee&tochange=0886ad6e6aaa I reverted to 4722b491cd0d in local build, the lag is gone. So, Bug 130078 causes the lag.

I get laggy behaviour if I skip the youtube step altogether, which I think is just bug 597338? Alice is it not laggy for you if you skip the youtube step?

(In reply to comment #1) > I get laggy behaviour if I skip the youtube step altogether, which I think is > just bug 597338? Alice is it not laggy for you if you skip the youtube step? No, These are totally different bugs.It is clear from regression window.

And this problem happens even if I hide Navigation Toolbatr(View > Toolbars > uncheck Navigation Toolbar). On the other hand, bug 597338 does not happen if I hide Navigation Toolbatr(View > Toolbars > uncheck Navigation Toolbar).

Hmm, I find it really hard to see a difference between the 2010-08-27 and 2010-08-28 builds on Windows (2000 and 7), but on Linux I can see a difference.

(In reply to comment #4) > Hmm, I find it really hard to see a difference between the 2010-08-27 and > 2010-08-28 builds on Windows (2000 and 7), but on Linux I can see a difference. In this case, you may need to scroll the long Bookmarks list .

And Bookmarks Toolbar should not be hidden.

I've been going through the Bookmarks menu and then the Bookmarks Toolbar menu item...

Ok, it is easier to see on Windows 7 if you turn off hardware acceleration.

Profiled this. We are spending a lot of time under nsRootPresContext::ForcePluginGeometryUpdate calling nsWindow::Invalidate. Bug 596491 should make that a no-op most of the time. Let's re-evaluate this bug once bug 596491 (and bug 597338) are fixed.

This appears to be addressed, Alice, can you confirm?

I can not reproduce any more. It is very well!