We unfortunately haven't tested our web viewer in Firefox. Let us know which platform you're running and we'll do our best to take a look in the new year (holiday vacation!).
In the meantime, give it a shot in a Webkit- or Chromium-based browser. I've had good results on Safari on iPhone, Chrome on Android/Macbook/Windows.
Runs pretty well (20-100 fps depending on the scene) for me on both Firefox 120.1.1 on Android 14 (Pixel 7; smartphone preset) and Firefox 120.0.1 on Fedora 39 (R7 5800, 64 GB memory, RX 6600 XT; 1440p; desktop preset).