Interesting! I'd be curious to see how well JavaScript Canvas maps to QuickDraw. Or, well, you probably just wrote to a straight byte buffer in VRAM, which sounds like the fastest approach of all. 
My 33 Mhz Quadra has a Radius Thunder IV card used to accelerate QuickDraw calls, so it's a bit more capable of handling 2D graphics than the average 68k Mac. It still doesn't handle Steven Troughton-Smith's color 68k port of Lights Off without visible slowdown and redrawing, so I'd like to see what it takes to get fast graphics on these machines.
It handles Marathon 1 (with low-res textures) and M1 mods like Trojan and Operation Tantalus pretty well, though.
My 33 Mhz Quadra has a Radius Thunder IV card used to accelerate QuickDraw calls, so it's a bit more capable of handling 2D graphics than the average 68k Mac. It still doesn't handle Steven Troughton-Smith's color 68k port of Lights Off without visible slowdown and redrawing, so I'd like to see what it takes to get fast graphics on these machines.
It handles Marathon 1 (with low-res textures) and M1 mods like Trojan and Operation Tantalus pretty well, though.