CPU - writing a GPU based NURBS mesher would be a massive job and probably not really worth it.
Now…you didn’t hear this from me - but in recent versions of Rhino 7 there is a non-autocompleting command “TestEnableMultithreadedMeshing” type it at the command line at the start of a session…and let me know if you see significant improvements in meshing speed.
It’s not supported at the moment - if you see problems, just restart Rhino. But please let me know how it goes.