The operators/owners are shown behind the address. Performance will differ and is based on at least those factors : 1) performance of the server itself 2) speed of internet access, also depending on your location.

My https://at.nostrworks.com has 6 vCPUs and 16GB RAM and can handle many more clients. It is hosted in Vienna/Austria and therefore especially suited for nostriches in Europe, but of course everybody has quick access.