I have a character in my scene that is less than 6k vertices and less than 2k faces. The face limit where it turns red in the stats seems to be 1k.
I have tried it on my desktop, a iPhone 7 and a Pixel 1. It runs at 60 fps on all three. Why is that limit so low?
There's an issue filed for this. https://github.com/aframevr/aframe/issues/3024
The answer is it shouldn't be.