Dont play with group.
Four player strokeplay gives reasonably more XPs than single play - if you can finish it. Some players have done this regularily with friends - good fun in company, and good XP growth.
Mind you: The most XPs from the least effort come with CDP: 537,000 XPs in the first year! Alas, 2,000 daily XPs are only available from day 374.
Also, pay attention NOT to play for XPs and levels only. The gaps increase mightily from L89 - a player might just burn out!