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- mod_php is loaded into every httpd process all the time. Even when httpd is serving static/non php content, that memory is in use.
- mod_php is not thread safe and forces you to stick with the prefork mpm (multi process, no threads), which is the slowest possible configuration
How to use it anyway
First, the module must be loaded:
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# A regexp such as \.(php|php4|php5)$ can also be used to support more extensions
<FilesMatch \.php$>
{{ SetHandler application/x-httpd-php}}
</FilesMatch>
References:
Official php installation and configuration instructions
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