Thinking through again, parallelize the gzip process for the backup/restore function could have a huge impact on your monitoring. If it use up all or a great amount of CPUs of your monitoring server you end up with a slowed down monitoring which is mostly not what you like to have.
If you really like to use a parallelized gzip you can pipe it through like omd backup <site> - | gzip > output.tar.gz. Haven’t tried this but in theory you could use this also across servers and use the direct call of gzip on both machines:
omd backup <site> - | gzip | ssh user@host 'cat - | gzip -d | omd restore -'