I actually don't recommend using a cache plugin as it may potentially conflict with wpforo. If necessary, you don't need to use a cache plugin, but you can use Cloudflare instead. You can exclude the forum from being cached by adjusting the settings in the page rule.

@marsm,

Here is a good list of plugins, however you should make sure all wpForo pages are excluded from your plugin like it instructed in this topic, you'll get the same notification in your dashboard when you install one of them: https://wpforo.com/community/faq/wpforo-and-cache-plugins/#post-37150