The Edge library sets the translateZ css property on symbol elements, this forces WebKit browsers to treat the element as a 3D element which makes vector imagery dramatically softer.
I have observed that unnessecarily treating elements as 3D also affects performance.
A few small tweaks to the Edge JS made it clear to me that this is an easy win for Edge, both preformance and visuals noticably improved after commenting out a few lines (where translateZ was being set).