Build Identifier: http://hg.mozilla.org/mozilla-central/rev/f2a500997116 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:20.0) Gecko/20121228 Firefox/20.0 ID:20121228030811 This does not happens if browser.library.useNewDownloadsView=false. Steps to reproduce 1. Create new profile and copy sample places.sqlite attachment 695227 [details] 2. Start Firefox 3. Open Library and choose History or Bookmarks in the left pane. And stay open Library. 4. Open any web page in main window --- observe page loading speed 5. Choose Downloads in the left pane once, (and then choose History or Bookmarks optionally) 6. Open any web page in main window --- observe page loading speed Actual results: Extremely slow loading web page when I leave the Library which chose 'new download view' opened once. ie. Step.4 normal speed Step.6 Extremely slow Expected results: Loading of web page should be normal speed even if I leave the library which chose 'new download view' opened once

Slow script warning appears: >A script on this page may be busy, or it may have stopped responding. >You can stop the script now, or you can continue to see if the script will complete. > >Script: chrome://browser/content/downloads/allDownloadsViewOverlay.js:930

Just duping since there's no point in keeping this open