This could be your browser/local machine or it could be because there are a lot of element on the canvas and when you try to move one around, it tries to snap to all the other ones.

I'm not sure what the best way around this is though, as snapping is a key feature. Any ideas?

Try to snap only to a few items? I'd suggest the outermost items and the closest items.

Perhaps holding a modifier key while dragging could disable snapping?

That's a great idea--I'll see what I can do.

i think that maybe a local problem for you, i tried chrome and firefox on windows and ubuntu.. no stuttering at all