Actually the next thing I want to do is something that is more oriented towards the speed area. It's nothing that will take along time, but since both versions here run on the same database I have to do the PHP and the PERL updates at the same time.
The first one involves the way the main topics are indexed. Right now it has to do a full table read when grabbing all of the main posts instead of using the indexes. So this is a bottleneck on larger forums.
The second one I want to put a limit on how many days worth of posts are pulled from the database. Meaning you will get a default profile option for how many days worth of posts you want to view, as most of the time people won't be worried about the older posts. This also is a bottleneck on larger forums.
Once these 2 things are done, then I'll be waiting on user feedback for what to concentrate on next. The 3 candidates will probably be the admin area, the user interface (my w3t area), or site integration stuff.