craftcms / craftcms/cms

[5.x]: asyncCsrfInput true or false negatively impacts page speed

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#18,022 6 comments 0 reactions 1 assignee View on GitHub

@timkelty is already working on this.

Since Nov 11, 2025.

bug
Dominant language
PHP
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Description

What happened?
Description
  • Setting asyncCsrfInput true - Creates an extra network request to the network dependency tree on page load which negatively impacts the LCP Core Web Vitals metric
  • Setting asyncCsrfInput false - Forces a no-cache server response header which forces a static caching layer to be bypassed, negatively impacting TTFB.
Image
Steps to reproduce
  1. set either setting
  2. run a pagespeeed/lighthouse test
Expected behavior
  • For a craftcms website to not to be negatively impacted by a feature we cannot control
  • asyncCsrfInput false should instead never set a nocache header - then we can be in control of when it should fetch a CSRF, e.g. when a form is "in view"
Actual behavior
  • No matter what setting is set, it negatively impacts performance
Craft CMS version

5

PHP version

8

Operating system and version

No response

Database type and version

No response

Image driver and version

No response

Installed plugins and versions

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