What does High Setup time mean in performance debug Table

Question

I am encountering an issue where approximatly once or twice a minute one request is facing a very high response time of 26 seconds. Its completely normal otherwise

Tried enabling the built in performance debug mode in Qa-config.php

I notice 99% of time is comsumed by Setup up where as control, view and theme is 0% relatively.

out of 99% setup time, 98% falls under PHP rest 1% under Other category.

This is resulting in very high waiting (TTFB) on the browser. - around 28 seconds...occasionly.

How can i debug this further ? and what does this Setup mean ?

Comments

Does this happen on specific pages? Question lists, question pages, user profiles, etc.

Answer 1

"Setup" is everything that's done before a page request is actually processed by the scripts in qa-include/pages/

It includes a few things like normalising the request and parameters (ie deciding which page script to use), setting up plugins and external users if you're using that.

If you're getting slowness in that part, it's most likely due to external users or a plugin that does some work before being called.

Try removing plugins and see if one of them is causing the issue.