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Slow javascript execution with Firefox 10

  • 2 replies
  • 22 have this problem
  • 2 views
  • Last reply by Dirk1967

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The site https://www.dexia.be functioned perfectly on Firefox 9 (and older). However, since FF10, it's become slow (sometimes resulting in the browser reporting javascript is slow and ask to terminate execution). Compared to Google Chrome and IE9 the site has almost become unusable (even IE7 performs better). Have there been any fundamental changes in browser rendering that may be the cause? Is this a known issue that will be resolved (the available versions FF11 and FF12 still seem to have the same issue with this site)?

Modified by Dirk1967

All Replies (2)

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Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration or the JavaScript JIT compiler is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

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Unfortunately, the suggestion above did not change anything. However, our impression is that the issue has a resemblence with the following issue, reported in 2007: https://bugzilla.mozilla.org/show_bug.cgi?id=385260.

Executing getComputedStyle() and getting the offsetWidth variable value in some cases take "extremely" long (usually <0.02ms, but sometimes up to 1200ms, called over 600 times). We have one case where Firefox consumes 50% on a dual core uP Windows system for a couple of minutes, and then gives the "Warning: unresponsive script" dialog ("A script on this page may be busy, or it may have stopped responding. [...]"). It seems like Firefox is internally looping and no longer response (the Firefox menu itself is inaccessible as well).

The number of tables (or nested tables) in a page seems to be the trigger for Firefox to start behaving "badly" and becoming unresponsive.

The issue has now been reported as a bug.

Modified by Dirk1967