It's too early to do benchmarks. Nothing in ClojureC is optimized at this point, so it would do very badly. I'm focussed at making it work first, then on making it fast. We'll get there.
That brings an interresting other question : How far are you into making it work completely ?
I'd say - optimistic estimates (for pessimistic, multiply by 2) - core language 1 more weekend, core library 2 more weekends after that. So far it's been about 3 weekends of work.
Contributors are always welcome ;-)
I'll finish up cljs/lua and i might give a hand :)