I’ve used the same hosting company for over 10 years and have never had an issue like this until now. Most of my sites use around 100 plugins and have about 75 pages each.
I was looking for a more modern forum, closer to phpbb, that works well with WordPress; mainly because I was tired of having to go through all of the setup that bbpress requires. I really like the unread posts feature. Yes, you can create this with bbpress, but I got tired of having to assemble bbpress each time I went to use it.
At the time when I wrote the previous post here, I had actually gone in and fixed part of the code wpForo uses. The deeper I went, the more I realized this plugin has more issues than I was willing to chase.
Coding a forum is a very difficult process. I have to give wpForo credit for making the attempt. It may look like a Porsche but it doesn’t do well with a Pinto motor under the hood.
I finally ended up using a different forum plugin. It too isn’t perfect but the author doesn’t blame their work on others, plus there are a several hooks and filters that allow you to customize the forum the way you want.
Sorry this isn’t the answer you were looking for. There just isn’t a simple fix for wpForo.