Should I choose the 15inch or the 13inch macbook pro retina?

This is my first Mac and I'll be replacing an i7 quad core Thinkpad. I currently use it for java web programming. I want to be able to debug in tomcat via IntelliJ Idea with postgres running and spotify working like a charm.

My fear with the 13inch is that it comes with a dual core and I think ti will overheat with my workflow.

What do you say?