I’m sorry to be that guy, but did you ever try it out for yourself?
Just starting Emacs took as long as a full regular Emacs elc-build, if not longer.
So not exactly faster by a universal standard.
Guile itself is making huge progress. There's ongoing work for JIT compilation as well. Andy Wingo drives this work. And he brings a lot of experience from work on the V8 Javascript engine.
I see no technical reason why guile-elisp should be any slower than normal elisp. It's just that some of the optimizations have not yet been put into place. After a switchover all the improvements from Guile will come for free in the future.
See the branches named "master", "lightning" and "wip-elisp" here: http://git.savannah.gnu.org/cgit/guile.git
It doesn’t take much to terminally derail an effort driven by only a single contributor.