I like changing the speeds. On the MX518 there is a + and - button at the top and bottom of the mouse scroll wheel. And with the software that came with it you can program at what senstivity you want to use. i.e I've got it set up as 400, 600, 800, 1200, 1600dpi and then on the fly in games you can change the senstivity. Personally I like it fast when I play FPS's but when I zoom in or use iron sight I like to drop it down quite low because I've got more control over it.