My Montana 700i freezes several minutes when i navigate with the map after after upgrading to software 15.20

It's a known bug. Seems introduced since 14.xx firmware. Please report to Garmin.

Thank you, how do i report to Garmin? Do Garmin follow this forums?

Sometimes Garmin employees read - and occasionally respond to - forum posts. However, this is not an official support channel. "Reporting" this would involve opening a support ticket. If it really is a known problem, it may not be worth the effort to open a ticket. OTOH, the more people who report it, the more likely it is to be fixed sooner rather than later.

you can open a ticket using the buttons at the bottom of this page:

https://support.garmin.com/en-US/?contactOverride=true&productID=699779&tab=topics

Options vary depending on time of day and, possibly, other things. If you have the choice of chat or phone, use those in preference to email. Nobody likes to wait on hold. But based on forum responses, email is a black hole. Requests in, nothing out.

I have sent Garmin a ticket and got answer from they. I sent them som pictures that showed what i mean.