In the course of fixing bug 455057, we found that removing a sRGB chunk from an image used in the browser chrome had a noticeable impact on Ts. In one case it made Ts go *up*, and in another case it made Ts go *down*. That it made any change at all is rather surprising, and will be an annoyance in the future if updating theme images causes random and unexplainable performance changes. The two images were: browser/themes/winstripe/browser/tabbrowser/newtab-aero.png browser/themes/winstripe/browser/tabbrowser/newtab.png The former is only used on Vista, the latter only on XP. Stripping the sRGB chunks from these images made Vista ~30ms slower on Ts, and XP about ~20ms faster. I've relanded the XP (newtab.png) image as part of bug 455057, since it's an oddity in our favor, but did not reland the Vista image since it's a regression.
this one is a real headscratcher - I'll put it on my todo list for june when I start up with moco again unless someone else wants to tackle it sooner.
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