And would you mind explaining why this is?
You can think of it like a flow of water in a tube and the LED being a turbine.
If you restrict the flow before a turbine then the speed decreases. If you restrict the flow after the turbine then it does the same thing becuase the water cannot move through through the turbine any faster.
It is the same with circuits, you are restricting the flow of electrons around the circuit.
Mowcius