UPDATE: We are testing a new forum. For those interested in these things the strong candidate at the moment is WPForo. The important criteria is not that it works as a forum but that it works as a forum AND integrates with the rest of our systems (Subscriptions, editorial, membership etc.). So far WPForo seem sto do all of that.
It will take some time to get it operational but so far we seem to have succeeded in importing most of teh existing forum into it on our development server. The performance issue that regular forum users are experiencing right now is down to the inability of BBPress (Current forum) to be able to cope with the sheer quantity of posts – despite our attempts it’s not something that can be fixed – so it’s WPForo in the new year.
The way we plan to implement it is in phases. Currently we are testing that it can exist NEXT to BBPress on the server without them falling out with each other. This is so when we launch it we can do so in a small, controlled way – probably as a replacement for just one current forum (Chat, bike, news, members, women). If that goes smoothly or after we iron out the bugs, we’ll roll it out as a replacement for all the forums.
We should not need to keep the old forum as an archive if we can successfully import all the topics back to 2009 and there be no performance issues. But we haven’t ruled out a partial import of say the last few years and retaining the old forum as some kind of read only archive.