Webgl2 performance issues

[msandin]

When using the plugin with the WebGL2 fallback on weaker hardware, performance seems to fall off a cliff. The performance is completely fine when using WebGPU or running natively on the same hardware. Examples:

• On my more-than-five-years-old 32GB machine with a 8GB 1070 it's absolutely fine in both scenarios
• On the relatively new 16GB laptop with a 4GB mobile 3050 that I also have in my household it runs at maybe 5 seconds per frame (note, not FPS but SPF)
• I have another report of unknown-but-weaker-than-1070 hardware where it runs "very badly"

In all cases switching to the regular Windows build fixes the problem, and in the laptop case I tried with WebGPU build in Chrome and that worked nicely.

Not using any lights doesn't save the performance, the problem occurs as soon as the plugin is loaded, which means it can't be easily "fixed" by making it a setting in a menu or automatically turning lighting of if the numbers are too bad. Making it possible to dynamically turn the effects of the plugin on/off would be useful for implementing that kind of solution.

[jgayfer]

Thanks for the write up!

WebGL2 will inherently perform worse, as there are quite a few limitations we have to workaround. That being said, we should still aim for it to perform reasonably.