gfi ground fault plug having 1 strange problem

Does anyone have a clue what makes a gfi outlet work? Outlet is also known as a receptical or plug according to some people & geographical location.

My saw runs good plugged into a 120v wall outlet with a standard type 15a circuit breaker, sounds good, has lots of power, cuts right through wood easy.

I moved saw to a different location with a gfi outlet one with red reset button & black test button on the side of the house. Saw runs & makes lots of noise, buzzes, hums, rattles, 75% less power, slow to cut wood, blade stalls out easy. This makes me think the motor brushes have gone bad.

I plug the saw into another outlet with a standard type 15a circuit breaker saw runs good again, sounds good, cuts good, lots of power.

Air compressor has a 120v motor but this motor has no brushes & the motor runs good on the gfi plug.

Air compressor run good no matter where I plug it in.

Saw with brush type motor runs good everywhere but on the gfi breaker?

Are the motor brushes sending an arc signal to the GFI is that the problem but why does the motor actually run and have very little power & make so much noise? What is going on?

The only things inside a gfi are current sensing transformer and breaking contacts, so I suspect the gfi contacts or wiring have high resistance and make the saw run weak.

Faulty outlet or faulty wiring to the outlet.

Ron

Might be that the saw is leaking a minuscule amount of ground current, that is making a borderline GFI attempting to trip.

I would eliminate possibilities: Take the saw to a friend or relative's home, and connect it to a GFI outlet. If the problem persists, then the saw has a problem.
On the other hand, if the saw works fine in this GFI outlet, your original GFI is defective; replace it.