Updated: 11 October 2026 · Applies to: CloudLinux OS
ImageMagick uses all CPU cores by default. Inside a CloudLinux LVE, where an account has fewer cores than the server, this causes heavy context switching and makes ImageMagick slow.
Fix (root)
Limit ImageMagick to one thread in its policy.xml (/etc/ImageMagick-6/policy.xml or /etc/ImageMagick-7/policy.xml depending on the version, or the config folder of a custom build):
<policy domain="resource" name="thread" value="1"/>
Alternatively, set the environment variable MAGICK_THREAD_LIMIT=1 for the web server or PHP.
