Thanks for your suggestions. I really appreciate it.

So, I finally got to the bottom of this. It wasn't WPForo. I was using a Redirection plugin to redirect URLs. Somehow it went out of control on two of the WPForo Topics. I replaced the Redirection plugin with regular .htaccess redirects. I didn't do this originally because I didn't realize that you can use regular expressions in .htaccess, but you can! Now everything is running  lightning fast again. Sorry for cluttering up the forums here with an issue that was unrelated to WPForo.

Thank you for letting us know TimRodman.