I want to edit a track. I have a new mac not sure what program I can use to do this. I downloaded audacity but it runs slow and choppy. I have a brand new mac that has hardly any programs on it.

"edit a track" as in?

Sound Forge remains one of the top editors, and I would recommend to a new user- easy to use, and ultimately powerful.

...but not on a Mac.

Depending on the edit Garageband can handle the basics.

Well shame on me, I have trained myself to ignore mere mention of any apple derivation. In that case I would say Logic Express, although my own experience with it is tinkering only, but I'm sure the mac pro's out there will vouch for, in a entry-mid level price range and skill level.

Logic Express is also great for an beginner. Also check out Ableton LE it has a $50 mail in rebate so you can get it for cheap right now. Garageband itself is a good program and really is just a dumbed down version of Logic, it's also free on every mac.