APC User Cache
Install APCu
apt update
apt install plesk-php81-dev zlib1g-dev
/opt/plesk/php/8.1/bin/pecl install apcu
echo "extension=apcu.so" > /opt/plesk/php/8.1/etc/php.d/apcu.ini
plesk bin php_handler --reread
systemctl restart plesk-php81-fpm