Your own experience is obviously completely valid and people can't be in a position to deny what you have seen, but time would be better spent to understand why their experiences were different from yours.
On the other you have no right to deny other's experiences. I can categorically say there is no lag of the rMBPs that I have been testing. I put them into 1920 x 1200 equivalent resolution in the Mac store (UK) for well over an hour and there was no sign at all of any lag. Indeed it was faster and smoother than a non retina macbook pro near to the machines. This was in Safari, on many different image and animation heavy websites including Facebook. It was also between applications, launch centre etc., general OS UI. All completely impressively smooth. EXACTLY like a number of others are starting to report. All of course running lion not ML, being in a Mac store.
The big question is why is there a problem with some and not others. It all points towards software in my opinion, like you said. Thanks by the way for posting those Chrome settings, very helpful for many I am sure.
For those out there still concerned that this lagging issue might be a deal breaker, my advice is not to be. It clearly is not being seen on many machines, so is not a universal hardware problem.