Increase max_children

install/deb/php-fpm/www.conf

@@ -6,6 +6,6 @@ user = www-data
 group = www-data
 
 pm = ondemand
-pm.max_children = 2
+pm.max_children = 4
 pm.max_requests = 4000
-pm.process_idle_timeout = 10s
+pm.process_idle_timeout = 10s