User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8) Gecko/20051111 Firefox/1.5 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8) Gecko/20051111 Firefox/1.5 After loading the image(URL) I discovered, that my mouse jumps when I move it over the tabtitle. I saw that the big PNG-image was used as the icon of the tab. It would be better to shrink the image only one time and save the small one into the cache, so it won't be shrinked each time. Or use a format specific icon. Reproducible: Always Steps to Reproduce: 1. load the URL above 2. move your mouse over the tabtitle 3. watch the CPU-usage rising Actual Results: The CPU-usage rised and the mouse jumped. Expected Results: No lagging. installed extensions: Adblock(deactivated) downTHEMall! FlashGot Browse Images

(In reply to comment #0) > It would be better to shrink the image only one time and save the small > one into the cache, so it won't be shrinked each time. Duplicate of bug 305986/bug 304561?

WFM. I don't see any lagging or "mouse jumping" (FF 1.5, Gecko 20051111 from mozilla.org; also FF-CE 1.5 mahowi, Gecko 20060131 using libmng to render PNG, on WinXP). That's with only two tabs, one empty and the other with the specified URL.

Yes, it's a dupe of bug#304561. Marking it so. *** This bug has been marked as a duplicate of 304561 ***

Gilbert: see if the problem goes away if you go to about:config and reset browser.chrome.image_icons.max_size to 512 instead of the default 1024. Your sample image is 725x711, which is too small to be caught by the preference.