PHP 8 and OPcache: recommended configuration for PrestaShop

PrestaShop is a large PHP application: thousands of files loaded on every request. That is why the PHP configuration, and OPcache in particular, has a huge impact on speed.

Which PHP version

• PrestaShop 9: PHP 8.1 to 8.4. We recommend 8.3, which is stable and fast.
• PrestaShop 8: PHP 7.2 to 8.1. Use 8.1 if your modules support it.

Before upgrading, test on a copy: old modules can fail on PHP 8 because of removed functions or stricter types.

OPcache: the setting that matters most

opcache.enable=1
opcache.memory_consumption=256
opcache.interned_strings_buffer=32
opcache.max_accelerated_files=40000
opcache.validate_timestamps=1
opcache.revalidate_freq=60

• max_accelerated_files: a store with many modules easily exceeds 20,000 PHP files. If the value is low, OPcache fills up and stops caching.
• memory_consumption: 256 MB is a good starting point. Check with opcache_get_status() that it does not run out.
• revalidate_freq: how many seconds between checks for changed files. In production, 60 is fine; after a deployment, flush OPcache or wait that long.

Other parameters

memory_limit=512M
max_execution_time=300
max_input_vars=10000
upload_max_filesize=64M
post_max_size=64M
realpath_cache_size=4096K
realpath_cache_ttl=600

max_input_vars is the classic culprit behind forms that “do not save everything”: products with many combinations or large translations send thousands of fields, and PHP silently drops those beyond the limit.

How to check what is actually applied

PrestaShop shows the PHP configuration in Advanced Parameters > Information. And if you have SSH, php -i | grep opcache gives you the command-line values, which may not match those of the web server: compare both.