I loved MDK when it first came out and I was eager to play it again. Unfortunately, the game crawls (VERY frustrating) whenever more than one or two enemies are present. I couldn't even make it out of the practice room, due to over and understeerage and plane unresponsiveness.
I'd expect this in Crysis perhaps, with all features turned up, but not for a 10 plus year old game.
My computer is more than up to snuff - It's 2.4 GHZ, 2 GB RAM. running WindowsXP.