Hi Lukas,
No, that is something completely different. The thing I adjusted is simply a PHP variable that is set within the plugin, that decreases the potential result set size.
php-fpm is the UNIX server process that handles the script executions – usually invoked when someone visits your site (when wordpress loads), or when makes an ajax request. It usually spikes when the cache is re-built.
It might have been a bit overloaded as I was conducting the tests. Usually, the php-fpm process will use a lot of CPU, but only for a very short amount of time. Unless you experience significant server downtimes or constant CPU overload, it should be fine 🙂