Is having 2 GB of memory not enough with the new Mac Mini?
If it's Safari 5.1 you're in the same boat as a lot of people. The recommended suggestion is bail out and go to Chrome, but I like Safari so I've stuck with it. I've completely removed Flash from my system (I sandbox it in Chrome), I trash Safari's cache once a week, I completely shut Safari once every 4 hours, and I never have more than 10 tabs open at once. That keeps it relatively stable, but I'm probably going to move to Chrome as it's a bit much for one app.