@tom s @Lorraine Lee If you need some setting advises, I use these in #FPM pool's php.ini file:

[f.haeder.net]
chdir = /
group = www-data
listen.allowed_clients = 127.0.0.1
listen.group = www-data
listen.mode = 0660
listen.owner = www-data
listen = /var/run/apache2/php7.4-fpm_friendica.sock
php_admin_flag[log_errors] = on
php_admin_value[error_log] = /var/www/.../phptmp/fpm-php.friendica.log
php_admin_value[memory_limit] = 128M
php_admin_value[session.save_path] = /var/www/.../phptmp
pm = dynamic
pm.max_children = 10000
pm.max_requests = 10000
pm.max_spare_servers = 15
pm.min_spare_servers = 5
pm.status_path = /pool-status
request_slowlog_timeout = 20s
slowlog = /var/log/php-fpm/$pool-slow.log
user = vuXXXX

So for my instance 128M is totally enough.