Transparent window performance overhead

Hey, wanted to be sure about something…
In the manifest we can set a window to be transparent (which we do)
what I want to make sure is - if the actual window is NOT rendered as transparent (let’s say we have a fully opaque background set by CSS)
will there still be an overhead to performance coming just from the flag itself compared to a none transparent (manifest) one? (when both are rendered as fully opaque in both scenarios)

I will try to find some info about it and update you here.