Okay, In fairness to subversion, I feel the need to amend my past statement. Subversion doesn't need to die, but all its poor implementations do. I finally got decent performance out of it, after removing Tortoise (Not even a Hoveraroud would have saved that one), Installing Ankh and a command line SVN tool. Both of which raised my times from, O(N) where N = Files in source, to O(N) where N = files checked out, or files modified since the last sync.
Which means, I ended up installing 3 tools, to get what perforce does with 1. On second thought, subversion can still diaf.