Post Processor Cache

To speed up responses, the AMP plugin leverages WordPress' object cache to more quickly serve the AMP response for a WordPress URL that was previously transcoded and validated by the sanitizers in the post-processor phase of the plugin. Each time the content on a page changes or a new URL is processed, the post-processing of the output buffer of the rendered template is cached for later retrieval. We call this post-processor caching.

Automatically Disabling of the Response Cache

Certain themes and plugins have randomly generated content. The content can be created by a widget, shortcode, template, or Gutenberg block. For example, the Twenty Seventeen theme uses a random generator for setting unique HTML ID attributes.

What happens when the content changes? It will not be found in the response cache. The plugin must reprocess the content and store it into the cache.

In essence, the cache can fill up with old content.

The plugin monitors for this condition. When it detects it, the response cache is automatically turned off.