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Understanding cache HITs & MISSes

3 min read

How to read the X-XSpeed-Cache header and tell exactly which layer served a page.

Every request to your site is either a HIT (served from cache) or a MISS (rendered fresh by WordPress). Knowing which is which — and which layer served the hit — is the fastest way to confirm caching is working.

The X-XSpeed-Cache header

xSpeed Cache adds a response header to every front-end request so you can see the cache status at a glance:

x-xspeed-cache: HIT (nginx)

The value tells you exactly how the page was served:

ValueMeaningTypical speed
HIT (nginx)Served as a static file directly by the web server, before PHP runs~5–15ms
HIT (php)Served from cache by the PHP drop-in (the fallback path)~50–90ms
MISSNot cached — WordPress rendered the page and stored it for next timefull page load

HIT (nginx) is the fast path you want. It means the static-rewrite rule is engaged and the request never touched PHP. HIT (php) still serves cached HTML, but through PHP — usually a sign the server-level rewrite isn’t active yet (check the Cache panel for the rewrite banner).

How to check it

Browser DevTools — open the Network tab, reload the page, click the document request, and look under Response Headers for x-xspeed-cache.

Command line:

curl -sI https://your-site.com/ | grep -i x-xspeed-cache

The first visit to a fresh URL is expected to be a MISS. Reload once and it should flip to a HIT.

Why some pages always MISS

A MISS on every load usually isn’t a bug — some pages are meant to bypass cache:

  • Logged-in users are served uncached pages.
  • Excluded paths like /cart, /checkout, and /my-account are never cached (by default and via your exclusions).
  • Cookies or query parameters on your exclusion list force a bypass.
  • Nonced or personalized content shouldn’t be cached.

The hit ratio

Your dashboard shows a hit ratio (HITs ÷ total requests over the last 24 hours). A healthy public site trends high (80%+). A persistently low ratio points at an overly-broad exclusion, a caching conflict, or a rewrite that isn’t engaged — start by confirming a plain post returns HIT (nginx).