I don't think WebGL is used with the original, since it was working just fine on my eeepc with linux (which does not do WebGL, last I checked). This new one barely works in chrome on windows on this T420 though.

I don't know what the cause is in my case, maybe WebGL on this thinkpad is really slower than CPU rendering on an Atom?

I'm using the exact same rig and testing same version of Chrome, and they seem the same. We're really just comparing WebGL to canvas. Note that I had to use WebGL because with asm.js, the cloth gets so dense that canvas couldn't handle it.