I’ve just landed a fix to a bug that has irritated me ever since page zoom started getting remembered for sites. It fixes a real problem you find if you both use zoom a fair bit, and load pages in background tabs. When you finally decide to look at that tab there is this little pause (or long pause if the page is large) and sometimes a visual jump as it re-zooms the content. It also changes where the page is scrolled to which is very irritating if you have just clicked a link to a specific line in some source code for example.
The fix was relatively simple, the problem is it causes a little extra time to be spent loading background tabs. About 3ms from the numbers I have. Normally this is small enough that you wouldn’t notice in comparison to how long a page takes to load. One concern though is how this impacts session restore where you have a lot of background tabs all trying to load at once. The tests I’ve run say pretty much what I’d expect, Firefox opens, all your previous tabs are displayed and start loading with no change due to this fix, the reason being that the additional time is spent later in the load cycle of the tabs.
Of course tests never quite mirror reality so I’d like all you nightly testers to keep an eye out to see if you notice a sudden change in the performance of the browser when you open it and session restore has a lot of tabs to restore. Obviously before filing a bug do the good thing and try it a few times both with nightlies with the fix (tomorrow’s should be the first) and nightlies without. If you do see definite issues then file a bug and CC me. Assuming there are no issues then I’ll be trying to get approval to land this for Firefox 3.1 in the near future.