I am on 125.65 release on OSX Mountain Lion.
The RubyMine process spins CPU at 100% for 15-20 minutes, then calms down for a little while and then starts again. In the status bar, I see "Looking for gems".
What's going on?
it looks like a bug, please file it in our tracker (http://youtrack.jetbrains.com/issues/RUBY)
But please attach zipped archive of RM's logs directory (Help|Reveal Logs in Finder)
Also it might be useful to provide cpu snapshot (see http://devnet.jetbrains.com/docs/DOC-1144 on how to get/provide it)
I'm using RubyMine 4.5.4, Build #RM-119.71 and I get the same behavior.
I find it possibly more than coincidental that I get a nag message about my upgrade license "running out" when I restarted RubyMine.
RubyMine is great for debugging, code completion, etc., when it works.
My only beef is that it is a bit sluggish and these CPU hogging lock ups make it unusable. :-(