I have turned off the list of who's online at the bottom of the index page (it still shows the stats though), as it is very server intensive, if you want to see who's around, then go to the quick links and who's online, as it will only load for those who request it specifically.
We are looking at a second server, but cannot see that it will be installed for a few weeks yet due to our host moving premises.
So we may well have to suffer a little up until that date (perhaps with a few more server saving measures), at least it is only periodic slowdowns at the moment.