Termie and I met Grand Fromnage on Saturday for a very useful discussion, about which you will no doubt hear separately.
He explained why the performance is so variable, so for you computer buffs: CA owns the server, which is now a few years old. It's a Dell server, 1U size and sits in a rack in Copenhagen.
The forum traffic is causing memory to max out, which in turn causes memory to be paged to disk. The disk is big enough, but this just slows down the system. So, at least, it needs more memory. DJet (our tech guru) has tried various memory modules but none of them worked properly.
GF had/has plans to replace the server this year. It would be a better spec, including a 10,000 rpm drive and more memory. So this will go into the pot with all the other discussions and plans.
Just on that topic, we currently have unlimited bandwidth. While some of the hosting services offer seemingly unlimited (or at least very high) bandwidth, apparently it really peaks at this time of year. GF is going to supply some stats about page hits etc. This will enable us to look around to see whether there is a better deal to be had. However we should bear in mind that there are other ideas for change which will hopefully increase traffic to the site (and probably consequently to the forum) so the unlimited bandwidth may become a necessity.
If anyone can get a deal on proper servers, please PM me. I can get something like 5% off Dell.
