Thanks for the report! Landing a fix for the issue (-b/glutin) right now—I had it queued but never actually got around to landing it.

Thanks, where can I run benchmarks (either the ones in your video or others) so I can compare it against Firefox? It still doesn't "feel" as smooth as Firefox, but then again that could be unrelated to WebRender.

I think it's not really ready for informal benchmarks like that. There are lots of random issues. Feel free to try various pages and file bugs, though.