We should make sure that we're not drawing more than necessary in composting layers because of rect coalescing.
Created attachment 129370 [details] Patch
Comment on attachment 129370 [details] Patch In drawRect: we examine the total area of all texts and do a single paint if they cover a sufficiently large fraction of the clip bounds. I wonder if we don't need something similar here.
s/texts/rects/.
I wonder that too. I'll look to see if CA does that already.
http://trac.webkit.org/changeset/109186
<rdar://problem/9082399>
This change was made to help http://ie.microsoft.com/testdrive/performance/mazesolver/default.html performance.