I don't know what happened, about 2 weeks ago my MBP got noticeably slower using Lightroom 4, it would take twice as long to render 1:1 preview, and moving images around would be really choppy. I didn't change anything or updated any setting. I even reformated and reinstalled OSX Mountain Lion and the problem is still there. I compared the performance to my friends same spec rMBP and his is much faster. Ideas? I did a pram reset also, Is there a hardware issue? The boot times and shut down is still fast, I'm guessing it maybe the graphics card? Ram issue? My system spec is 2.3 Ghz, 8gb of ram, base 15" rmbp model. Very frustrating.