Differing between outside walls and outside walls on the inside of a part.

[TurboJens]

Hi, I have a project and I want to reduce print time by printing walls that is inside the part and invisible after fitting. I have tried to find a way to speed up these inside-outside walls by adding a modifier and increasing outside speed but that adds extra walls inside the parts so it actually takes longer time and uses more material.

Only the outer circle is visible, how could I define the large inner hole as a inside wall to speed things up?