Using a virtual dev environment (with vagrant) seems like a good move if you're stuck on windows. You get to develop with software that runs on linux using whatever tools you're comfortable with on windows.
I only briefly looked through the README, but why is this necessary? Does The Real RVM (tm) not work (well) on Windows?
it doesn't work at all on windows afaik. Pik is a decent recreation, but not quite as good as rvm imo.
Is still Ruby and Rails slow as hell in Windows?
No. The old one-click installer used VS6, and the new one uses MinGW and GCC.
You can always use jruby
ruby startup speed is most annoying on windows. jruby is not a fix for this issue by design.
How long does it take for MRI to startup on windows?
interpreter startup with tiny script is ok but loading unit tests by rake command is slow.