Have you ever solved 100% CPU usage issues? If yes, what did the trick?

Hi, I am a WordPress Developer.

I have been researching about the 100% CPU usage issue but ending up having dead ends.

So, have you ever solved a 100% CPU usage issue? If yes, would you please explain how did you solve it?

Like I don’t need a brief answer, but what was the root of the problem?

Is it a theme? or a plugin like Woocommerce which is running too many CRON jobs, etc.

Could be any of those things.

Have you installed Query Monitor? It may provide some insight: https://wordpress.org/plugins/query-monitor/

Your host may not support this however services like New Relic can help provide insight as well.