Paths with markers have too large of repaint rects View http://www.w3.org/Graphics/SVG/Test/20030813/svggen/painting-marker-02-f.svg and then try inspecting one of the paths with markers. You'll notice that the rect the inspector highlights is huge! (Another way to demonstrate this would be to animate a path with a marker via. js and then watch the repaint rects in Quartz Debug.)
Created attachment 16770 [details] test case
*** This bug has been marked as a duplicate of bug 33012 ***