There's a few not modded servers out there with active admins, most that I tried were better performance wise
The CommunityZ for example runs on a dedicated machine in europe, way smoother than official servers for me when the population hits high/full.
On official expy servers after a certain player pop zombies can no longer move freely and get stuck everywhere for example
Hackers can occure everywhere, but if you report them they get banned pretty quickly on all vanilla community servers I tried, and to most rumours of admin abuse I came across people cannot give any proof and it turns out to be just salt.. especially when servers run no mods like CommunityZ or Spaggies servers to prevent any admin god mode abuse.