This panel include settings that control Caching and Cache Levels (see section High level caches) for the current Collection, including AJAX Forms to avoid caching of security crumbs.

Starting in version 4.1, it is only possible to enable page caching when using AJAX forms at the same time. This prevents issues with cached Crumbs (nonces). Crumbs are a security & antispam feature that requires serving a different random "crumb" string to each user. We cannot cache a single string and serve it to multiple users. That would defeat the purpose.

Also, AJAX Forms prevent comment and message forms from being indexed and cached by search engines like Google. This makes it harder for spam bots to find and post to these pages. Note: If they still post spam, the comments go to the moderation queue anyways.