The forum takes a lot of time to load.
Please have a look at your performance score
If you consider using some caching service/CDN I believe it may help a lot. Cloudflare is free and very easy to configure and their caching will reduce the load on your backend server which seems to be struggling with keeping the forum up.
I would happily offer any assistance I can if needed w.r.t to webhosting, so we can identify the issue.
Thanks for your attention