[kingfishr]

I had this problem right when I started using rbenv. Eventually with some help I realized that just starting bash was slightly slow, and that all the various bash scripts that rbenv runs were compounding this for a 2+ second startup.

In my case, everything was fixed by moving the the things that only need to be run in login shells out of my ~/.bashrc (where they should have been in the first place).

See the bug I filed against rbenv at the time:

https://github.com/sstephenson/rbenv/issues/70

Since that time, I've been using rbenv exclusively (development and production) and it's been great.