Feb 2014 Update: this issue has been resolved. The problem in my case was a failing hard drive. Continutation of thread from 10.8 forum subsection after upgrading my computer to 10.9... I've disabled spotlight on my external partitions after... After installing 10.9 last night, I restarted my MBP this morning, and it seemed to do fine until about 8 pm, then I got a perpetual spinning ball so bad that my network connection dropped, the dock would not open up and I had to wait and wait and wait some more. All I ran today was Firefox, with about 15 tabs open. However experimentation regarding the number of tabs vs memory usage seems to indicate there is no correlation to more tabs equaling more memory usage. The MacOS was functional when I left it, came back an hr later and Spinning balls. Oh, yes, when I tried to purge memory in the terminal, I now get a new message "that's not allowed". I also noticed when I finally got it restarted, all most all of my memory in the Activity Monitor was shown as being used. Drat. Memory management might be better, but I think overhead is higher. This what I wanted to avoid. I acknowledge as OSs advance they become more demanding. If I want to keep using this computer, and not lose my mind, I'm going to have to upgrade RAM... This is what Activity Monitor looks like after installing Mavericks- On Startup: Is this something I should be alarmed about? Where before, using 10.8 Activity Monitor showed a substantial amount of memory as free on startup, with 10.9 it basically shows all of the memory as allocated? Is this a different way of showing the info or is 10.9 much more of a memory hog? I also noticed that Mavericks has disabled the memory "purge" command in the Terminal. What should I make of that? Thanks!