cant upgrade my 2009 iMac 2009 20" with 2GB for a few months but need to upgrade to 10.9.4 to install Yosemite.

I am currently running 10.8.1 as a fresh install of Mountain Lion which runs fine, but I dont want to install Yosemite and have OS hang and beach ball on me.

Not running anything to intensive, at most; Sublime, Spotify, terminal, Firefox