From what I gather, it is minimal to little or no gain at best when all things is said and done.
Memory? If it is SuperFetch, it does take memory space for keeping things that might be used in the near future "there". In short, it is being effective with space it can use, if a program needs space, the OS can allocate accordingly. It is a caching system that is in addition to a virtual pagefile already used in the OS.
If you want a game to perform better, setting that program on a higher priority on the task manager would prioritize the CPU for it and memory cache.