I got a copy of Scannerz a few weeks ago to test a WD external drive I had. It comes with something called "Performance Probe" that shows a summary of the system loading, memory use, etc. etc. In any case, before I went from ML to Mavericks, with Safari and Mail running, it was showing typically about 2G of RAM in use. With Mavericks, it's showing between 2.3-2.4GB, even when it isn't doing that much. I popped open Activity Monitor to take a look and found the following two seemingly new processes are really, really fond of eating memory: com.apple.IconServicesAgent mds_stores If seen the IconServicesAgent go up to 400MB, and mds_stores can run up to a few hundred meg as well. It's pretty easy to guess that mds_stores has something to do with mds, but exactly what? The bigger question for me is IconServicesAgent. Anybody have a clue what this does and why it's eating so much memory? If it wasn't for these two this thing would be running possibly less that ML...faster too.