You can load any game written in BYOND in FireFox and have the performance issues show almost immediately.
But it's especially egregious in mine and I don't know why, as I've done almost nothing besides add a few basic extensions to the base engine to create a somewhat-usable 2D Second Life-esque platform (with far more expansion capability) and FF just dogs on it. Space Station 13 REALLY makes the problems stand out.
A URL to something that shows the problem really would be useful here. I can profile and all that, but it would be good to be profiling something that actually shows the problem.
Tell ya what, give me a few hours to unwind from my gig this morning and I'll see if I can't get my old server actually up and online and port-forwarded. If I can (this assumes I actually have spare ports on the router) I'll send you the link, as I see that No-IP just sent me a renewal notice for the game's domain name anyways.
Nope. 2D application and still can't get over 20FPS in Firefox (meanwhile, Chrome and Edge get a solid 60 FPS, in spite of their own quirks.)
Looks like they skipped fixing their WebGL 1 issues.