Cache warming on low-traffic WordPress sites

If you have a WordPress site that relies on time-based static page caching (like W3 Total Cache), you may notice that the low default cache timeouts (1-5 minutes) aren’t really working well for sites that receive a low amount of traffic.

In these cases, cache warming provides a great option to make sure every visitor gets a fast TTFB response.

I recently wrote a PHP script to enable cache warming based on a sitemap. (Which both Yoast WordPress SEO and Google XML Sitemaps provide.)

You can find the script and setup instructions by clicking on this link.

Caching strategy for low-traffic WordPress deployments

Let’s talk about caching strategy! Sites fall into one of two categories:

Low amount of content (~20-30 unique posts or pages)

Use a long cache expiration time (24 hours or more), but make sure that the cache is flushed when any content changes. (This is usually configurable in the cache plugin.)

Schedule crawls generously, as crawling will be fast as long as cache hasn’t expired. Crawling every 15 minutes or so is no problem.

Large amounts of content (> 100 posts or pages)

If you have a lot of infrequently accessed pages, the problem gets harder to manage. Crawling hundreds of pages will take a toll on your server, racking up high CPU usage. The only option here is to cache indefinitely, to only flush parts of the cache that are affected by a change, or cache for even longer periods of time (over 1 week).

For caching, I recommend the free Cache Enabler.

Schedule crawles less frequently, once per 1-4 hours. Keep track of the time it takes to run a crawl. If your web host enforces low PHP timeout the crawler might get killed before crawling all the pages.

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