Make sure that you’re only using the Jetpack modules you want.
Most of Jetpack is designed to speed up your site by taking load off of your server, like our site accelerator https://jetpack.com/support/site-accelerator/ or stats https://jetpack.com/support/wordpress-com-stats/ subscriptions https://jetpack.com/support/subscriptions/ and related posts https://jetpack.com/support/related-posts/ which are all processed on our end (rather than hammering your database as these features traditionally do).
With that said though, the more Jetpack modules you add, the more your site has to initially process, just like it would if you added a separate plugin for the features, so always make sure you’re only using the features you want.
Regarding overall speed and load, here’s an excellent independent report: https://mattreport.com/jetpack-speed/
However, you shouldn’t be seeing any significant load when publishing posts. Are you saying that you hit Publish on 9 to 10 posts simultaneously?
I only use the modules I need, and these are a speed boost module, a lazy load module, and a related post module. At the same time, I open 10 posts and the load starts, and by excluding the jetpack plugin and opening 10 posts at the same time no such load.
So this is merely when you have the posts open in the editor, with no actual task being performed at the time?
Are you speaking of the load on your server, or CPU load on your computer itself?
