I have the following problem in all my Wordpress apps in the VPS. Both admin and frontend have quite acceptable speed. TTFB is more or less 100-200ms. However, when I publish or update a post in admin, the TTFB becomes more than 10sec. Some times even reach 20secs.
I got a similar behaviour in apps with Woocommerce during the checkout process. When a user places the order and he waits for the thank you page.
I tried to talk with the support, but they don’t see anything wrong in the server’s side. I am lost on how to “debug” this and find the actual problem.
Things to keep in mind:
- It happens in every app with Wordpress
- It happens only on publish/update a post or placing a Woo Order
- The rest of the website speed is acceptable
- PHP v.7.2