I've been working to cleanup and optimize our WordPress site and noticed that after removing WP Rocket from my plugins list (We're using SG Optimizer for our primary caching plugin), the homepage load time ballooned out to 10 seconds. After contacting the webhost, they found this cookie being applied to the homepage that is excluding it from being cached:
Antonia-Nikolova:~ antonianikolova$ curl -IX GET https://www.midstory.org
HTTP/2 200
server: nginx
date: Thu, 07 Jul 2022 15:29:23 GMT
content-type: text/html; charset=UTF-8
vary: Accept-Encoding
access-control-allow-origin: https://www.midstory.org
set-cookie: PHPSESSID=5e46dc3d2372c4aa67bf732d8ea1177e; path=/
expires: Thu, 19 Nov 1981 08:52:00 GMT
cache-control: no-store, no-cache, must-revalidate
pragma: no-cache
x-cache-enabled: True
link: <https://www.midstory.org/wp-json/>; rel="https://api.w.org/"
link: <https://www.midstory.org/wp-json/wp/v2/pages/4766>; rel="alternate"; type="application/json"
link: <https://www.midstory.org/>; rel=shortlink
x-httpd-modphp: 1
x-endurance-cache-level: 0
x-nginx-cache: WordPress
host-header: 6b7412fb82ca5edfd0917e3957f05d89
x-proxy-cache: MISS
x-proxy-cache-info: 0 NC:000000 UP:SKIP_CACHE_NO_CACHE
They commented that I should find the thing that is creating the cookie and disable it to allow the homepage to be cached. However, I'm not sure what is creating it. I checked my WP Optimizer settings before disabling it to make sure there were no exclusions added for the homepage, and likewise for SG Optimizer. Are there any Built-in WordPress settings that could cause this to happen? I'm not sure where to start to track down the source.