I mean.. it does depend on what you mean by "faster than C" of course. Writing the straight forward naive solution in Mojo for some problems can produce code that can run on both CPUs and GPUs and be super fast. Can you get the same performance from C? Probably.. with lots on intrinsics and one code base for GPUs and one for CPUs, where the GPU codebase might even be multiple code bases for different vendors.

I would say "faster than C if you want to keep your sanity and don't have infinite time". It doesn't roll off the tongue though :P