Kate you forgot the next upgrade...

5.11 Version 10.9: "Puddy-tat" wink

I upgraded to Mtn Lion and it did slow some, but I had only 4 Gb... added 8 Gb more for $56 and it's MUCH snappier !! so I think you've got to boost RAM if you don't want a performance hit. It wasn't bad w 4, but this is much better.
David (OFI)