QUESTION: "Compatibility" settings explanation?

[Trackmaniack]

Okay, so I've been tweaking around with settings to find the best mix of performance and quality--and have a question for the more experienced maniacs. You go into Configure-->Advanced-->Display-->Compatibility, and what do those settings mean? I obviously understand some things like "Advanced Steroscopy," and "AGP Usage," but the rest I could use some instruction on. Any help? Thanks in advance, guys.

[eyebo]

D3D9Ex makes it easier to tab in and out of the game and go from windows to fullscreen quicker. I know that much.