What do you need?
Next, open RubyMine’s Info.plist:
mate /Applications/RubyMine\ 1.0.5.app/Contents/Info.plist
Find the line with value 1.5* en change it to 1.6*.
Start RubyMine and check the ‘about’. It should look something like this:

Enjoy. It does feel snappier on my side.
On a sidenote: You can set the default Java version via the ‘Java Preferences’ app.
Miljaar. Heb ik dat hier nu juist in het Engels geschreven? ;)