I'm looking to get a decent monitor for design work, photo editing, etc. I've looked at the Thunderbolt Display as well as some from NEC. I've found a couple 4K monitors that might be good options too, but I'm curious to know how well a 15" 2014 rMBP can drive a 4K monitor. Does it have any lag, or cause much stress on the GPU? Any recommendations for a good monitor?