I've been pulling my hair out all day with this issue. It was nice and zippy yesterday, but today? AARGH!!!!
Hopefully it's an SQL issue on the server that will be resolved shortly. I just rent space, I don't administrate the server.
Without actually knowing any details, my bet would be that the issue has nothing to do with the board software, but rather something else on the hosting provider's server (or something real popular causing spikes in traffic to the server) or something with their backbone connection, etc. Assuming this is on a shared server, i.e. this site isn't the only site running on it, you really should pass the issue onto them.