specify your own causes less fragmented files on your hard dirve. specify it 1.5 * your ram or 2.5 * your ram. But the same amount for both min and max since then it would make your file swapping(vitual memory) less messy. More generous the amount you specify the better results i have heard. But besure you have enough space on your hard dirve for the amount you specify. Result less cpu work to find files (not a great noticable speed up) but good for the computer, less fragmented files.