to host a pool you need a pretty good server. its not a problem when the pool first starts out but as it grows the wallet server starts to max out on processor.
as an example heres my pool wallet. this handles 1200 miners and only just manages to hit the max my processor can give out. my old wallet used to flatline. the reason why it flatlines is because the deadline calculation queues once the cpu max is hit. if the pool doesnt have enough resources the processor will constantly flatline as the time between each block doesnt give it chance to stop a cool off. it gets caught in a loop of requeueing and eventually stops the wallet from communicating as its trying to do to much.
below is the ram.
the wallet vm spec's
below is the screenshot of the system monitor from my pool as my wallet is hosted on a seperate vm.
most vps hosts only offer up to 4 cores. some ive seen that do 6 cores or more usually go for around 100$+ a month for rental. as your looking more towards a dedicated server instead of a vps.
most users who set up a pool wont even consider future growth. or review the resources their pool is using to assess for upgrades.
Our DB is newer and we can only load to the block if it stuck not above, doesnt matter if we pop with api some blocks, only works if the db is newer then the pool db, already fix the problem thanks to community.