So for a couple of days now I've been running ESXi on my Dell R710 and I've tried a lot but I am still unable to run more than 2 accounts per VM without it becoming unstable. This is a software issue and has nothing to do with the hardware being 'bad'. After doing some research and finding out that basically everyone has this problem I decided to look for a solution luckily someone else already mentioned it: using Vmware Workstation Pro instead of ESXi. But the problem is that Workstation Pro requires a compatible GPU to enable 3d acceleration. And the other problem is that server parts aren't compatible with a lot. So a recommendation and some Googling I found out that the GT 710 with a X8 pci-e slot should work. I decided to get the 'Gainward GT710 1GB' because it's the cheapest, has a fan and is the only one I could find sold by a Belgian store. I hope it will arrive in a couple of days and that it will work.
Late night edit: Fulcrum just released a super quick update, so here I am trying to run my bots again as quickly as possible so I can go to sleep. Not sure if I should be happy that they can run again or if I should feel sad because I can't go to sleep yet