Im currently on a mid-2009 13inch MacBook Pro 2.26 GHz, 4 GB RAM, SSD. Id like to do my photo editing on my personal computer as Ill be cut off from my schools digital lab. There I used iMacs with i7 quad-cores and 16 GB RAM, using Photoshop, and everything was smooth and quick. My laptop is quite sluggish using Preview and GIMP (I plan on getting Photoshop CC and Lightroom). The images I edit are 48-bit color/16-bit grayscale, 200-megapixel TIF film scans. Although their size is considerably bloated (the actual resolution is closer to 40 megapixels), I like to edit them in this size for the marginal benefit, before downscaling to a useable 30 megapixels or less. The editing I do is general photography stuff: color balance, sharpening, retouching, HDR scanning, and so on, with at most two or three images open at once, in addition to some browsing in the background. My question is, would RAM be my limiting factor? Would an $80 upgrade to 8 GB help my current MacBook at all, or can I just invest in a mighty new rMBP? Im almost certain the answer is nothat my processor is also the bottleneckbut Im hoping Budget wise Id be comfortable getting a topped-out 15-inch rMBP with the GT 750M. Im also considering building myself a workstation PC with a 10-bit 4K monitor (not that 10-bit colors would be so critical for me). That said, Id really like to have the mobility of a laptop (I wouldnt need to carry it much, but at least be carry-able) and OS X. A Mac Pro would be too expensive and building a PC myself offers better negotiation of what I need (dual FirePros are not so important). Plus theres always the opportunity to invest in a nice external display, too, and the Retina screen is gorgeous from what little Ive played with it. I imagine the 2.8/4 GHz i7 in these MacBooks would be sufficient, correct? Would there be a way to utilize CUDA from the 750M in Photoshop and Lightroom, or is it safe to stick to Iris graphics? Ive done some research and it seems CUDA is a bit of a tricky thing to get up and running for this case. What about driving a 4K/5K monitor at some point? What other options would I have?