Comment by Rohansi

I meant slower vs. WebGL rendering, which requires JS. Each triangle is rendered as a DOM node. There can be thousands of triangles in a single model.

The gallery has been updated with more models. Compare the same model in PolyCSS vs. Three.js:

https://polycss.com/gallery/?model=205023689 (13 fps)

https://threejs.org/examples/#webgl_animation_skinning_morph (60 fps)