Pro tip for levelling I found:
Stand in a closet that has a light switch and a door.
Spam open and close the door
While doing that, have mouse cursor hovered over the light switch and click every 2-4 times you open/close the door.
(Having to alternate because the XP stagnates when you spam one of them too much.)

It's about 4-5 xp every 1.5 seconds without XP book.
Very good for when you need first level after picking inefficient perk so you can quickly go from
180% interaction speed to 140% and have a more decent experience using items.

I found this out at 800xp and spent about 5-7ish ingame hours to grind up to level 1, it was worth the slight cramp in my left hand.

Hope this helps for anyone reading