Introduction
Caching is useful—until it starts to distort reality. After enabling an optimization plugin, server-side cache, or CDN, a website may load faster but still display old prices, an outdated form, an old phone number, or outdated JavaScript. The site owner updates the data in the admin panel, but the user continues to see the previous version.
Symptoms
It is especially dangerous to cache pages that contain forms, language selectors, personalized sections, and thank-you pages. In cases where a website needs to respond to user actions, a static copy may prevent form submissions or display incorrect information.
What is being checked
- Which cache is enabled: CMS, server-side, CDN, browser-side
- What Cache-Control headers are returned by the pages?
- Are forms, shopping carts, thank-you pages, and personal areas excluded?
- Is the AJAX/API response from the form cached?
- Is there CSS/JS versioning after updates?
- How is the cache cleared after content is updated?
- Do multiple cache layers conflict with each other at the same time?
Correction Process
First, we determine how many cache layers are actually in use. Then, we check which pages can be fully cached and which should remain dynamic. Exceptions are set for forms and APIs, CSS and JS files are versioned, and cache purging is tied to content updates. If a CDN is used, its behavior and purge process are checked separately.
Normal result
After corrections are made, public pages remain fast, but changes to prices, text, forms, and language versions are reflected for the user. Dynamic scripts should not depend on the old static version.
Conclusion
A cache is a performance-enhancing tool, not a black box. If you don't understand exactly what it stores, you might end up with a fast website that quickly displays incorrect data.