It uses SVG, so it will speed it up a lot. Unfortunately for things like a force layout in a graph, the main bottleneck will be JavaScript calculating the positions.
You're right, it doesn't at the moment. But the whole point behind WebRender is vector graphics are much better suited to GPU rendering - there's no reason SVG couldn't be targeted eventually.
EDIT: Realizing you are Patrick himself, of course you know this...
