I don't mean this as a 'Please search before you post', but you might want to take a look at these two threads, there was some great discussion in them I think. Mind you they're a few months old so I don't know if they should be bumped.
http://www.tfproject.org/tfp/showthr...ighlight=speed
http://www.tfproject.org/tfp/showthr...ighlight=speed
Take a look at them, they're a good read
