Not sure how fast it should go, but I'm using the supplied charger, lock screen says fast charging and is gone up 40% from 40 to 80 in just under an hour.
Much slower than my moto turbo 2.
It charges slightly slower than a 6P (about 10 min longer according to reviews). 1h20m to 1h30m or so should be a full charge on the XL. I charged my XL from 19% to full in about an hour.
Make sure the phone says "charging rapidly" on the bottom of the lock screen, and make sure the cord is plugged in all the way to the wall brick - if it's not it may not fast charge.
This is very interesting to know. The HTC 10 has 3.1USB and quick charge 3.0 but you dont receive calls when your transfering files to your PC at 3.1 speed