You should first note that CPU readings shown on our website are actually for your game and not the physical server itself. Minecraft is a multi-core CPU game, however there are still certian parts of the game that can't run in mutliple cores, eg the Server Thread. It is important to maintain your server so your Server Thread does not reach 100% or your Minecraft will lag.
Here are the top 5 most common causes for Server Thread to overload:
- Too many entities! Perform Clean up - Clear up that 500 Chicken Farm
- You have used up your RAM - this forces the java garbage collector to work harder.
- Constant Exploration - Just let the world load up chunks for all players
- World Bug / Plugin Bug
- Complex Redstone circuit
How to find out the cause? Just send us a support ticket! We will put a profiler on your server which will provide all the details we need to figure out whats going on.