Allocated unit size in Windows 7 x64?

Well I hear the higher the "Allocated Unit Size" The faster but will take more hard drive space visa versa. I am conserned wether the highest(64k) have impact on performance versus the default(I heard its 4k) conserning games and HD Videos(Mostly 2-4gb). Will I see a noticeable boost in games, applications, videos, and pictures(mainly when I open a folder with a lot of pictures it takes time to load a thumbnail preview of it, will this speed it in any way?) I know hard drive rpm affects game loading time but will 64k do any good at loading or anything else? Better game stability or maybe improved performance?