1.86 core 2 duo.
That is also some of the problem, go up to an i5 and you take a hit on battery.
As long as it does what I want it to do battery is the most important thing for me.
I use ableton live 8 and it works perfectly, I use Serato Itch with an Allen & Heath X: One controller and again never had a single issue.
I have DJ'd for 3 hours on the battery when I forgot my ac adapter, and still had loads of battery left.
After 18 months or so of owning this I still get 5-8 hours from this thing. I see people with 2012 models moaning that they are only getting 3-4 hours.
I went from a 15" Pro with the core duo and this felt far faster, 18 months later I am not doing anything different with it so there is no reason for me to feel it is lacking in any area.
If I upgrade to ableton 9 and then it feels sluggish or I get issues then maybe I will upgrade, but it would be fine. If I used an i7 for a few weeks and then came back I might just find it slower, but doubt it.
I can get a 2012 13" with 128gig HD new for £845 as my daughter is at Uni, so £345 to swap should be a no brainer, but even still I am not sure it is worth it.
I was waiting for the Retina 13", but with 256gb it is £1699 and that is just not worth it.
So to sum up, this does every thing I want and well, I may get £500 for it, but it is worth far more to me than £500.