Lag Issues

I know this may be a sore subject for some, but I've noticed a little while ago: for a couple of months, every time I tried to access my profile, meessages, the forums, anything, there was just this massive lag in loading the page. Is this a sitewide problem, or am I just having a problem with my own computer? If so, any suggestions for how to fix it if it comes up again? (It mysteriously disappeared a few days ago, but I get a feeling it'll come back.)