​@Youri Moskovic  For #1 you should be able to disable this no problem in the Messenger settings under Show Launcher -- create an audience filter that removes it for the mobile users based on certain criteria. 

Here’s more info on using the show launcher option:
https://www.intercom.com/help/en/articles/1155368-control-who-can-see-the-messenger-launcher-on-your-site

It may be possible to do based on browser or OS version, it would be great if there was an option specifically for mobile here but I don’t know if that option exists. 

For #2, in my experience because the messenger code doesn’t affect load times in any major way but if you are finding that, it could be worth exploring to see why.   If you are noticing page performance issues, what are you seeing? Maybe the team can address those for you.