I really wish there was a way for the browser to blit pixels to the screen in the shortest amount of time possible. Like talking directly to the GFX hardware using a restricted API like the Canvas 2d context.
I don't have high hopes for something designed by committee.
The Chromium team are experimenting with Low-latency (desynchronized) canvas, although I haven't been able to measure any differences in latency, the only difference is that desyncronization will cause some render issues.
I guess latency is a "full stack" problem where you have to design everything with low latency in mind. eg. keyboard, keyboard driver, render framework, gfx driver, and screen.