its just not well optimized. runs fine for most people but some have issues of big cpu usage
outgoingCall in this thread has a really good computer. The issue isn't caused by anyone's personal computer not being up to snuff, it's just some specific hardware quirk that affects people at random ( so far as I can tell. )
the software is certainly unoptimized as shit though, and its coded like complete ass. The only way I could really fix it would be to create an entirely new program ( as well as ditching godot, probably ). That's something I neither want to do nor do I really have much skillset outside of making stupid games in Godot.
I'd recommend checking out PNGTubeRemix: https://mudkipworld.itch.io/pngremix It's a much more stable and feature complete fork of my software ( although, theseus may argue how much of a fork it still is lol )
It is also never too late to learn some 3D modelling and rigging, if the 3D avatar is what you really want. buying a commission be damned, i guarantee you what ever crap you can make yourself will be much more charming