Too many beach balls -- reinstalled Flash
I'm passing this along in the hopes it may help someone else...
I upgraded to Snow Leopard a few months ago and to 10.6.8 when it was released, but I was having frequent slowdowns while browsing, many spinning beach balls. I tried many things: clean install, different browsers (Safari, Firefox, Chrome, Opera, Camino), and using OpenDNS for DNS, nothing really helped.
In one discussion someone suggested reinstalling Flash, so I uninstalled flash, restarted, did clean install of Flash, and everything seems vastly better now. This Adobe page has all the links and instructions: http://kb2.adobe.com/cps/865/cpsid_86551.html#ostype=m,
My thanks to that poster and maybe this will help someone having a similar problem.
iMac, Mac OS X (10.6.7)