Not sure if I can blame the weak amount of vram Radeon 4670 256 chip and my nearly empty 500gb magnetic hard drive in my 2010 iMac on all too frequent beach balls in Mavericks. My iMac has 12gb of RAM and it flew on ML 10.8.5 even with the hard drive half full and the weak vram.
A clean install of Mavericks did zilch for me.
Wish I waited to install this on my iMac.
So for laptops it might be great, but in this iMac users case, it was not.
You can blame it on the rotating platter of that HDD of yours. Even if you have 64GB of RAM, you can still frequently get beach balls if you don't have an SSD. I tried this on my Mac Pro before.