The Fatty’s definitely slower than my other bikes but it was never meant to be fast. I was out on mine at Swinley on Sunday morning and didn’t have any problems keeping up with some of the other riders on the trails
Seconded, on my local flat trails it’s about 10% slower but 50% more fun.
As mentioned before it’s a trail bike, so for beaches you will need to buy and fit a pair of Surly Larry tyres as the Floaters dig in and flick up too much sand making it hard work.
For bivi Fat bike riding look at the Mukluk or the Pugsley etc as they have rack mounts, or travel light weight