SKevo Attacking a free service must be a great achievement.
Maybe it would be a solution to release all the related code. I think given the size of your service, there will be a relevant group willing to spend time improving it.
Regarding DDoS, eBPF could offer a way to block attacks without wasting too many resources. Depending on the layer used to attack the server. It could also help to strictly limit the resources a forum could use. This could be archived with containers, but also with pure resource limits (possibly limited by the process structure). This way, an attack on one forum does not affect the others.
