Problem: The client was experiencing severe performance issues when editing posts in Gutenberg with many images, where the server CPU would spike to 100%. Initial tests indicated excessive REST API calls for each image due to WPML settings, but further investigation revealed the issue persisted even with WPML disabled. Ultimately, the problem was traced to the Redis Object Cache and the PHP handler used. Solution: We initially suggested setting Media translation to 'Translatable' and syncing media manually from WPML → Settings → Media Translation to ensure proper handling by WPML. However, the root cause was identified as the interaction between Redis Object Cache and the PHP handler. Switching from LSAPI to PHP-FPM significantly reduced CPU usage and network traffic. We also provided links to related known issues with Redis and WPML, and recommended configurations to improve performance. The main caveat is that its benefits are most pronounced in LiteSpeed/CloudLinux environments, while on Apache or Nginx stacks PHP‑FPM remains the standard.
If this solution does not apply to your case, or if it seems outdated, we highly recommend checking related known issues at https://wpml.org/known-issues/, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If issues persist, please open a new support ticket at WPML support forum.
