You shouldn't need to tweak anything on your laptop. USB2 is easily fast enough for DVD burning. In fact, even firewire is fast enough, even though the data rate is a little slower than USB2. (not sure if you have a firewire port or not)
I have used a 16x burner burning at 16x on the firewire port on a Samsung Celeron 1.8ghz laptop with no tweaking required.
Just keep your hard drive defragged on a regular basis for maximum read speed. I don't recommend trying to copy "on the fly" on the laptop at anything faster than 2x though, as the internal combo drive probably won't keep up at anything faster. Much better to create the files on the hard drive and burn from there.