Polygon winding

I was wondering if does matter much
to change polygon winding with
GLFRONTFACE …?? Will it slow
down rendering to change winding several times each frame…??

First of all stay with the simple rule of OpenGl:
“Do as few state changes as possible”

To your problem:
Depends on how often you change the winding .I think 2-4 times per frame is okay but if you change it some 100 times per frame like in the thread-example from the superbible(perhaps you know it?) you´ll slow down things alot.