Logic Pro X performance difference between iMac i7 3.5ghz (non-Retina) and the i7 4.0 ghz (Retina)?

Hello - on the verge of getting an iMac - it's for Logic Pro and some video editing with Premiere Pro (don't *really* need the Retina screen though) - i'd just like to get an idea of the performance difference (especially in Logic Pro X) between the quad i7 3.5ghz (non-retina) and the quad i7 4.0ghz (retina)?

I use loads of plugin instruments (incl. big Kontakt libraries) and effects with just a few audio tracks (only ever record max a couple of audio tracks at a time)

Thanks!