Ok,
I've got some hard details on the current server and performance and as most expected it's almost certainly a mySQL bottleneck. I'm pretty confident we can get things up on running well for half the cost JREF is currently paying, and then it's just a matter of $$$ to improve performance even more (SSD vs SATA more cache etc etc).
Put your hand up if you have experience with -
* CentOS
* mySQL
* vbulletin 3.7.7
And are willing to contribute some time.
The current goal would be to move the forum as is to new hardware to stabilise performance, and then at a later date upgrade the forum software itself. Suggestions and experiences on the latter are requested. vBulletin as a project has gone downhill so it will most likely mean migrating to other commercial or opensource forum software. That will mean lots of whining from people who like things the way they are
My current favourite is
Xenforo, which was developed by the original vBulletin lead developers. One thing I think is important is native support for different screen sizes (eg cell/tablet). All suggestions appreciated.
The other issue is of course funding. I suspect JREF has little interest in continuing to financially support the forum so we'll have to look at a donor/advertising/whatever model. Again, your input appreciated.