Concerning the forum itself, I think it's probably a custom one, to add reputation system linked to to whole website (at least just a bit customed).
Chrome is great at memorizing form fields when thne is errors, so perhaps try to use it.
I think the server is a bit overloaded, and the solution would be probably to upgrade it. If it's a matter of cost, why not ask the (happy :)) users to donate for it (for year costs).
In France we have great servers starting at 30 euros monthly (Online.net).