If your vehicle is showing power windows roll up or down much slower than usual, here are the most likely causes and the parts you'll need to fix each one.
Dirt buildup or dried-out rubber weatherstripping creates excess friction, making it hard for the motor to push the glass through the channels.
The electric motor that drives the window wears out internally over time, losing the torque needed to move the heavy glass efficiently.
The mechanical assembly that lifts the window can develop frayed cables, broken plastic guides, or worn gears that bind up and slow down movement.
If the door internals were recently serviced, the glass or regulator may have been installed slightly crooked, causing the window to bind in its tracks.
Internal electrical contacts inside the switch can become burnt or dirty, restricting the electrical current flowing to the motor.
If the battery is weak or the alternator is failing, the window motors won't receive enough voltage to operate at full speed, especially when the engine is off.