I've never had cider or the old nrepl.el crash or freeze on me, they've always worked fine. I develop on Mac OSX and Linux, what platform are you on? And what Emacs version? I tend to be on the latest GNU releases. Are you using a GNU Emacs or something else? If you're on Mac, I highly recommend this distribution [1]
[1] -- http://emacsformacosx.com