I get what he is doing, he is using some kind of bot that changes his IP by literally every second that passes and opens multiple instances of the site, that seems to overload the map and the chat counter (it counts like 999999999999 different users by second so of course it gets crashed) and that's why the chat and the map get crashed, also why the site is getting slow. He tried to spam the IB too but I rangebanned him before he could continue (rangeban because I banned him like two times and figured he would keep going precisely because of his constant IP change)
It's as easy as banning his browser or IP range from accessing the site, I recall hearing that somehow if you fucked up badly the site would redirect you to a rick astley video instead of bernd.group (I think it was if you tried to run javascript on the browser console or use inspect element too much). Why not do that to him?