Drawing performance does seem to be a bit sluggish compared to Chrome, Firefox, or even IE11. I guess it's a side-effect of the alpha-quality Dart integration. At this point, it's just a dev tool. There is probably quite a bit of overhead in areas where it kinda hurts.
Anyhow, for a GPU status report, check: chrome://gpu/
There is also a flag for enabling an FPS counter: chrome://flags/#show-fps-counter