Jumping doesn’t use stamina. When you are fatigued just start jumping and watch stamina recharging. You don’t have to release shift, just keep it pressed while jumping and keep running after stamina is 100% again.
You can open many doors in less than 2 seconds bypassing the slow “use” system they implemented in the game. Just keep the button pressed (in this case is default E) and move from door to door.
Fun fact : gnomes can also be collected by shooting them. It’s more fun watching them pop up in colors!
I’ve got more, i just didn’t recorded yet. I will edit.