I would expect that the extra members would slow it slightly but for me this has happened in the last few days. A decent PC should handle 30 off users requests and 10 or so members images and attachments.
I used to have to put a wait statement in my thumbnail grabber so as not to fetch the pages too quickly. Now the script can take up to 10 mins to run. It hasn't progressively slowed down. Its fallen off a cliff. Something has happened.
I sent a PM to Arcana yesterday but he must be away for a short break. If there is anything I could help with then id do it. Can't have my favorite web site down... But it seems as tho its definitely a server side issue. I would try getting wire shark out on it and see where all the bandwidth is going. My hunch is a zillion emails per day flogging viagra....