57571 2011-03-31 13:24:42 -0700 We spend time in updateLayerPositions() for every layout, whether or not layers changed 2012-04-17 14:29:53 -0700 1 1 1 Unclassified WebKit Layout and Rendering 528+ (Nightly build) All OS X 10.5 NEW http://cnn.com InRadar P2 Normal --- 1 simon.fraser webkit-unassigned hyatt jamesr jchaffraix koivisto mitz simon.fraser oldest_to_newest 377397 0 simon.fraser 2011-03-31 13:24:42 -0700 When cnn.com does layout, there are a lot of calls to RenderBox::computeRectForRepaint(), via RenderLayer::updateLayerPositions(). It's inefficient for the following reasons: 1. We don't track whether any layers actually changed, so we may not actually have to do any work 2. We're walking down the RenderLayer tree, but for each layer walking back up the renderers doing computeRectForRepaint(), so it's > O(N) 377399 1 simon.fraser 2011-03-31 13:25:51 -0700 <rdar://problem/9216902> 377415 2 simon.fraser 2011-03-31 13:50:01 -0700 Ideas here: 1. remove the repaint code from layers (hyatt says it's old) 2. have layout detect when a layer is moved or resized