Recently one of my larger sites, that runs on it’s own VPS, was experiencing high CPU usage.
What I was really trying to find out was what specific file could be causing the problem. I wanted to know if it was one particular thing making all the noise. This however did not prove to be easy.
I read a bunch of articles about how to make WordPress use less CPU and there were a number of different things that can be done. What I tried first however was installing the W3 Total Cache plugin.
Once I had configured caching the difference was immediate. You can see in the graph below exactly where the caching plugin was installed.
No more maxed out CPU for now.
Another thing you could try is by reconfiguring the way WordPress runs it’s CRON jobs.
It’s important to keep monitoring these things though, every day it can be a good idea to check your servers and make sure nothing out of the ordinary is occurring.