Hi Kartoffel!
By 'goes wrong' I mean that after moving in a straight line, box starts sliding towards the left, if frame rate is low (just run the code above, hold E and press mouse left). You can see those numbers on the screen, they go for 'velocity.x, y, z and bounce.x, y, z. Y should be equal to zero all the time, but on low frame rate it slightly changes..
As for the frame rate problem, I can't understand why, but it's still there.. Box will land on the different distance away from the camera, if I change fps from 60 to 20/30.
Greets.
Edit: I'll try to explain on the picture as well