All the problems I had were either
a: self inflicted
b: performed without adequate back-up
c: done as an upgrade, not a clean install.
d. trying to fix things myself without coming here first. (these guys really know their stuff)
After some pretty disastrous results, once everything was done as recommended, my computer has NEVER run better. As a matter of fact, it's running so well, I keep waiting for the other shoe to drop. I haven't even bothered updating to 10.10.1 because I'm having no problems with any of the issues it addresses.
Also, I have 4 gig of ram and it runs fine, FAR better than it ever did running Mavericks.