When nsImageFrame::FrameChanged is called, and the image frame is visibility: hidden, we don't need to invalidate. This saves a lot of calls and reduces CPU usage. Test Case: http://www.animecity.nu/mozilla/IMGTest/hiddenStorms.html There are 7 hidden animated gifs in the test case. Without this patch, CPU is about 25% on my system (PIII-933 on Win2k). With the patch, CPU is 0%

I wouldn't mind someone confirming CPU usage on http://www.animecity.nu/mozilla/IMGTest/hiddenStorms.html Include CPU Speed, CPU Usage, OS, Build.

I do see about 25% CPU usage on win XP trunk build 2002052908

os/2 mozilla rc2 plus privates, 700mhz, w/o fix: idle: 56.62% busy: 41.99% intr: 1.39% w/ fix: idle: 78.91% busy: 20.51% intr: 0.58%

Comment on attachment 85476 [details] [diff] [review] Patch to check if invisible It might be nice to solve this problem more generally. However, this seems OK if you think it will help more than it hurts. (How often are images hidden? How long does it take to check the style data? It probably does...) >+ const nsStyleVisibility* vis = >+ (const nsStyleVisibility*)((nsIStyleContext*)mStyleContext)->GetStyleData(eStyleStruct_Visibility); Could you use const nsStyleVisibility* vis; ::GetStyleData(this, &vis); instead? You certainly don't need that second cast.

David Baron: Done. The whole style casting thing is also done in about 6 other places in nsImageFrame, and that's why I had it like that originally. Is there enough performace inprovements using your method to create another bug to convert those 6 over?

Comment on attachment 88265 [details] [diff] [review] Patch to check if invisible r=dbaron. It's not a performance issue -- it's a typesafety one.

Comment on attachment 88265 [details] [diff] [review] Patch to check if invisible sr=waterson, nice!

fixed