After using Niresh 10.9 Mavericks for a few days, unfortunately, my Quick Look for certain types of images stoppped working and Preview became very laggy. For some reason, it still works with most documents, however. I am currently running the NVIDIA Web Drivers, and this is really my only complaint so far. This problem seems to be somewhat common in Mavericks, from what I can see by quickly Googling the issue. I would appreciate it if someone could provide some help, or maybe upload their Library/QuickLook folder (just in case I broke any plugins).