I've noticed that Q2A sends several headers to prevent caching on all pages:
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
However, for old questions the chance of them changing is quite low. So wouldn't it be beneficial to remove those headers if a question is more than a week old, or set them to cache for at least a few hours?
Also, would it be at all feasible to cache pages server-side, or parts of pages? If a user is logged in there will be certain parts that can't be cached, but a good chunk of the HTML should be cacheable, right?