This doesn't make sense. WebGL is as GPU accelerated as the other young'ish GPU accelerated terminals, except that they're not running in the browser, which should(tm) make them run faster.

On the other hand, rendering is just one thing to benchmark, there is input latency (already mentioned in this thread here somewhere), but also (terminal / PTY) bandwidth throughput. This is three categories where 2 of the 3 are not related to "GPU acceleration" at all. :)