I bought a rMBP but I'm regretting it for some things. Mainly two: 1) The Retina screen is gorgeous, but all the non retina stuff looks blurry and my 720p videos, too. I just need to play them at full res, not scaled. 2) The UI lags like crap. I wanted a notebook to last 2-3 years. This one, although costed me 2000, lags while doing nothing!!! Should I get something else? Is the cMBP screen so horrible for the glossy and so heavier? Is a downgrade to the 13" possible (I'd love portability)?