Overview
An interesting glitch I ran into yielding 75 exp for a non combat running loop that is roughly 2 minutes long and repeatable.
The run
I found this glitch in the Soviet Installation region, as soon as you move to the area with optional mission that rewards you a lock pick you can go back and start this glitch to get yourself a few extra levels to make life a bit easier.
First teleport to Base Camp of Soviet installation.
and just run the map as if you were doing it for the first time (all the enemies will be dead since you’ve beaten this section.)
Get past the train section.
Go into the building and up the second floor.
Climb the tower
Aaaaaand … just slide down this rope. for some reason every time you ride this rope you get a “+75 Stealthy” exp reward.
The reset
Now proceed to the next camp, this section is pretty linear so you can’t really get lost and teleport back to the beginning as many times as you wish. Enjoy.
After doing this a few times I average 2 minutes and 20 seconds per run.
FYI: I am playing on Survival difficulty, not sure if that changes the effectiveness of the glitch.