If you have encountered the bad UI performance issue on your MBPr 13, you may take a try on JDK 9 b38.
'[macosx] Performance problems with Retina display on Mac OS X' is listed in its change list.
1. get Intellij IDEA 14 from http://download-cf.jetbrains.com/idea/ideaIU-14-jdk-bundled.dmg
2. get JDK 9 b38 from https://jdk9.java.net/download/
3. execute 'ln -s /Library/Java/JavaVirtualMachines/jdk1.9.0.jdk /Applications/IntelliJ\ IDEA\ 14.app/Contents/jre/jdk1.9.0.jdk' in Terminal
Of course, currently JDK 9 is not officially supported in Intellij IDEA and it is a early access release.