Given Flash's atrocious performance profile, I'm surprised and impressed that this works at all. That being said, it chews an entire core on my computer to render the game at about 20fps, and the audio is nearly a half-second latent. Another way of looking at this is that Flash bytecode on a Core i7 today has caught up to half of where native bytecode on a Pentium I was 14 years ago.
I got 78.2 FPS on 'timedemo demo1', on an i7 920 @ 3600MHz, Flash 10.0.32.18, Firefox 3.5.5, Windows 7 Ultimate 64-bit. It was perfectly smooth. The audio lag (~200ms) seems more likely an architectural latency issue than a performance-related one.
It does appear to run without glitches. But your comment indicates that you never played the original Quake. Which ran at 60fps, software-rendered, on a Pentium I, with no audio latency.
