Due to some duff data, one of my terms retrieved in the graph was 1014 chars. The rendering (where all the vertices whizz around initially) was horrible - maybe 1-2 fps.
Obviously I shouldn't have duff data, but maybe some kind of optimisation is needed to truncate fields before they hit the renderer (with an indication that they have been)?
I've had similar issues - both truncation and word wrapping would be useful for labels