Reducing CPU usage

[Ecky]

A buddy of mine was running a Direwolf20 server on his AMD Phenom x6 machine for a while, but after a while the CPU usage grew to be too much and it began to run poorly (block lag and such). We moved the server over to my Intel i5 (Ivy Bridge) @ 4.8GHz with 16GB of RAM @ 2133MHz and initially it ran great. Over the past few weeks the CPU usage has been growing steadily, with 4 people very active on the server and using a lot of the mods. I'm up to 80-95% CPU usage (20ms avg tick spiking to 50-80 at times) and I have a feeling within a few days the server will start to become unusable on this system too. Problem is, I don't think there's faster hardware to run this on, period.

What can I do to help improve performance? Why is CPU usage growing like this? (also is this the correct section for this question?)

 

[Chaka]

Just set a CPU limit

 

[Ecky]

I'm afraid I'm a bit ignorant about java arguments and the like, how would I go about doing this? Or do you mean set the affinity to <4 cores?

EDIT: Would not limiting the CPU available to the server cause the average tick to go up, and things to run worse? I'm not looking to free up CPU for other things so much as prevent the server from growing to use so much CPU that it's unplayable.

EDIT2: I should probably add that, while I'm pretty tech savvy, I don't have a lot of experience with MC servers and none before this with mods. I don't know how or if I can disable mods, or if it can be done on an already established server to improve performance.

EDIT3: Trying the arguments found in this thread.

 

[UniZero]

Don't run the server from the machine you run the client on. Eventually you will have issues because you are putting more strain on your hardware.

 

[Ecky]

Well now, those arguments did the trick. CPU usage is down something like 90%. Looks like I answered this one myself, but thanks all!