windows and door locks barely move and act like they're not getting enough volts

Hello, the power windows in this vehicle run off of switch control of the motor, and do not appear to run through any kind of module. Therefore, it's a straight power / ground situation. Something is occurring that is depleting power to the circuit at the time it slows down. It will be necessary to test the circuit to determine what is happening. Since it's related to power door locks on the driver's side, I would lean towards inspecting the master switch that includes locks and windows. Certainly, a common power or ground circuit could also be in question, so it would warrant testing instead of just replacing a part.