To lookup RenderSVGResources for a certain RenderObject, we're using getElementById, which has been identified as a bottle-neck.
We discussed to cache RenderSVGResource pointers in the SVGRenderStyle, though that's dangerous, as we have to be sure we're not referencing dangling pointers.
So I'll propose a HashMap<String, RenderSVGresource*> addition in SVGDocumentExtensions. Patch following.
Created attachment 53426 [details]
Committed r57659: <http://trac.webkit.org/changeset/57659>
http://trac.webkit.org/changeset/57659 might have broken Qt Linux Release minimal