Hello,i read a lot here in this forum and would like to thank wayne/ and all the other peoples wo thred the thing forward. I have a rMBP 2.4GHz/8GB and have the same problems (Open 10 Safari Windows and MissionContol, and the Safari Scolling/Resizing issues). But at least for the Safari issue i have a definite solution with the new 6.1 version which can be downloaded at apple developer center. All the lag/hanging problems are gone, and it seems that they put the latest WebKit into Safari. No probles with the previous lagging sies like TheVerge. Facebook runns now perfectely smooth, even when scrolling with the MightyMouse. For the UI (Preview/MissionControl...) lags we have to wait for 10.9 which will hopefully sove this issue.
The core of the UI problem is the fact that retina technique does upscale the resolution to the double (in my case from 1920x1200 --> 3840x2400), render the things there and then apply the retina smoothing while downscaling it to the desitred retina pixel rate. In fact the whole UI is running on that high resolution. This all does the graphic card, and not the CPU, or better sad --> The CPU renders the UI elements to a high resolution and the GPU does the smoothing retina effect when downscaling it to the desired resolution. (2800x1800). If there are a lot of windows to handle with big memory areas the graphic card can't get htis fast enough. The technique behind is really old, and was part of the OS since 5 years, i remember. At least for Safari the render problem was resolved with the new 6.1. Hopefully they solve the UI lag (which annoy me not so much) will be solved in the new 10.9 version.
Apart from that i have another question. My Previous rMBP was stolen !!! I bought a new one. ******* anoying (i am from germany, and when we speak out the word ******* means that something was really really bad) I went to the police but without any results. Apart from the FindMyIphone/Mac webpage where you could lock the device when found, is there any side on apple where i could register my serial number or something ?