Build Identifier: http://hg.mozilla.org/releases/mozilla-beta/rev/097049b2438f Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20100101 Firefox/12.0 ID:20120321033733 This is only Firefox12. Menuitem highlight is slow/lagged by mouse hover when link url status is shown. Reproducible: Always Steps to Reproduce: 1. Bookmark a lot of bookmarks into a folder so that menupopup overflow 2. Open the bookmark folder 3. Mouse hover bookmark item and wait link url status is shown 4. Move mouse up/down quickly Actual Results: Menuitem highlight is slow and lagged. Expected Results: Should not Regression window Cannot reproduce: http://hg.mozilla.org/releases/mozilla-aurora/rev/55ee63484487 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0a2) Gecko/20120229 Firefox/12.0a2 ID:20120229042012 Can reproduce: http://hg.mozilla.org/releases/mozilla-aurora/rev/fcaf9e4c7965 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0a2) Gecko/20120301 Firefox/12.0a2 ID:20120301042012 Pushlog: http://hg.mozilla.org/releases/mozilla-aurora/pushloghtml?fromchange=55ee63484487&tochange=fcaf9e4c7965 Triggered by: fcaf9e4c7965 Boris Zbarsky — Bug 722641. Back out bug 598482 because it reduces perceived responsiveness in some rare cases. r=tnikkel, a=akeybl

Open Library and import.

Screen capture: http://youtu.be/Vx5fMeOWSBA