Rspec runs 200% slower with rubymine launched spring

I just started using spring for an older project (rails 3.2). If I start spring outside of rubymine, running rspec for all tests takes about 2 minutes. If I stop spring, run any spec from rubymine, then run rspec it will take nearly 5 minutes.

Is it the teamcity formatter that is adding all of that overhead? Or is it something else?

Note that if I kill rubymine the specs will run at the usual speed.