That's my experience too, except that I'm not using three.js, just WebGL. At this very moment I'm trying to elicit an in-browser machine-vision app that records go games on a go board if you mount your cellphone on a tripod over the board, with the idea of integrating it with an Emscriptened KataGo to give kibitzers real-time feedback. This would have been insanely ambitious for me three months ago, and now I'm hoping I have it in good enough shape to test at the go club tonight.