Well, it may not be keeping up with the new versions but at least it does cover a non-trivial subset of the standard implementation. :-)

I have not tried it in many years and I don't know how much faster or compatible it is. Nevertheless, I think it's a good thing that an "outsider" is looking at performance issues.

As far as I know it's essentially a one-man's effort. One could imagine that RStudio or Microsoft would be able to improve R performance substantially if they wanted to.