CPU Load Suspiciously High at Random Times

Hello,

I’ve been struggling with this issue for almost a month now. Our website uses the Xstore Theme and we are on a LiteSpeed server with MariaDB and PHP 7.2.

Over a month ago we started seeing strange CPU load. It seems like there is a PHP process that stucks and eats 1 of our CPU cores. If it stucks two times it consumes 2 CPU cores etc. The thing is that this continues for exactly 1 hour and the process stops after that without being killed manually. However at this time it is possible that it will start for another 1 or 2 times. Our host says that the only thing they see is that the file: index.php is causing the high cpu usage and that there is a stuck PHP process there, but this can be due to anything…

Here is a screenshot from today’s high cpu load: https://prnt.sc/ozy0zm

However the thing is that it stops by itself without being killed and most of the time it is like that for exactly 1 hour! However I have saw anomalies as in this screenshot: https://prnt.sc/ozy1ap where it starts and stops for smaller amount of time. 3 nights ago it has stuck like this for 6 hours.

I have tried disabling all of the plugins while it has been stuck and still nothing… There is not a single report for our plugins or theme that say high CPU, we are also using them on different websites and they do not do such things…

Another thing is that we constantly see the logs and there is no bot attacks or anything suspicious. So, I’m struggling from what else can this be and has anyone else experienced the same behaviour.

Thank you,
Best Regards,