Need some help with Linux and DA - TransIP VPS server

At transip.nl we have a VPS ruing with DirectAdmin. 1 website is now ruing on the server, wordpress/woocommerce, however, causes a lot of problems. PHP-FPM has an extremely high CPU usage. This makes the website slow.

I thought everything was fine, but I can't solve this one, I've looked up and tried everything. It would be nice if someone could take a look and tell me how to fix this.