[csarva]

I used rbenv for a while but what killed it for me was the huge startup lag it adds to every invocation of ruby or any other bin installed via a gem. I was seeing delays of 4-5 sec which disappeared when I switched to RVM. The universe of tools and integration is also far better in RVM land (though this may have changed more recently).

[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.