There's no easy way to assign a single profile to multiple groups at once. Instead, I have to go to the Groups view and click on each group I want to add the profile to, click the profile tab, click Assign Profile, find the Profile I want to add, then click the Assign button. Doing that for each group is tedious.

Instead, I suggest the Profiles view have an option in the Action button to be able to add whichever Profiles are selected to add to Groups. I imagine the resulting view would be a list of groups with a checkboxes to select which groups to add to.