Had all forgotten about a firefox add-on called YSlow. My development site scores 77 but your site scores 93 on the landing page and between 85-90 on the menu pages!!
YSlow did give some tips for you to look at 'Add expires Headers' and 'configure entity tags ( ETags )'.
Both are apache stuff. Perhaps you know how it works. My site has the same problems ( and quite a few others
) but i just let a friend look at it. He's the server guy so to speak ;)