Salut Stief
I don't know, haven't used it yet. My contribution thus fas was only opening the banmstoo' solution to other platforms. He runs it on a lowly K6 350, so performance of Tor and privoxy should be acceptable on any mac supporting os x. The clear limiting factor here is the bandwidth provided by the Tor system. Also, you may reach sometimes a Tor proxy from a network banning P2P or Gnutella....
Ciao