For using ReadyBoost which one is the best file system format. I am using FAT on USB drive. I found that using NTFS will offer more better performance. Other than this there are FAT32 and exFAT also. Among this which one is the best that will work. I have a 4GB drive which I will like to optimize for readyboost. But before that making a suitable partition will be more better. I am also having a external usb hard drive. It can help me to gain more performance.