Nothing out of the ordinary here, you could try reducing to less workers but I don't think that will help much. Are you running worker via crons or daemon?

I am running through different hosters (dedicated rack, kvm and also shared hosters) and my hoster does specify things like php process limit, memory limit, script runtime etc...

maybe you can get some more information from your hoster?

@Frend @Hiker Idea is to put up a simple phpinfo.php with the all-famous 2 lines: <?php phpinfo();. Then copy-paste the details here. Yes, shared hosters have their cheap prices but mostly for limitations, like no federating software with a worker daemon in background. Also other limitations can be CPU usage, RAM and HDD allowed or else you have to upgrade your hosting package to a larger one.

I wrote a "mailer" script, that comes from the old-times of the Internet where you can sign up with such service and collect points to book mails with your points and send them to other members. It has a self-managing part and reduced mail-delivery per click done on the homepage. My then-hoster (shared) asked me to shut it down while it was totally resource-friendly. Just as an example why root servers are often a better choice where you have more freedoms but more responsibilities, like administrating the Linux OS on it.