i did a small performance test on my windows machine with a DMC compiled version [63d91f0b87] 2010-10-05 16:37:40 UTC:

  *  Using localhost http clone for sqlite(~20MB transfered) 3 minutes running against a local "fossil server" service, CPU load goes up to 90%
  *  Using file copy clone for sqlite 1 minutes<br>which is infact a filecopy followed by a rebuild

I think, these times are OK(2 minutes for 20MB), if we remember, that running the http-variant uses 2 fossil instances and all traffic is checked by firewall and virus scanner and that fossil isn't designed as a high-speed html server.