This isn't really proof that Scheme will be faster than C, and in fact doesn't really mention Scheme at all, except to show that it is a language that supports call-with-current-continuation as a primitive operation.

What I got from the paper is that using continuations with intensional equality (that is to say their contents are the same) can be used to dramatically speed up a program. And so, a primitive way to create intensional equal continuations would be a potentially worthwhile primitive for a language.