RSS timed out, admin login slow

I’m confused. My wordpress works fine from the visitor’s end. All pages load quickly and there are no delays at all that I can tell. But the RSS and Atom feed links time out in every reader and validator. In Firefox or Internet Explorer, if I load the RSS URL I have to wait for about 2 or 3 minutes before the xml will finally show up. The same thing happems when I try to log in to the admin area: I click the login button and wait several minutes before it finally logs in. Once I’m logged in to the admin area everything seems to work at a normal speed except that publishing new posts seems to sometimes take a while, too. My first thought is that the database is moving very slow, but the only areas that are slow are logging in, RSS/Atom, and sometimes publishing a new post. I have several other database-driven sites on this same hosting account and they’re working fine. I’m running version 1.5.2. Any help is greatly appreciated!