I'm sure there are plenty of good people out there giving him good advice. I have compiled a list of 14 tips that is very comprehensive and valuable, IMHO.
Besides those, I'd strongly recommend that he take a look at the "perception factor". That is, some pages load fast, but because of scripting on the client or poor HTML, it takes a few extra seconds to appear fully to the user. There is no amount of optimization you can do on the server to address that. You can ask the user to buy a faster machine, though.