Higher numbers selected here will result in the cursor whizzing around your screen with little effort. If you wish to increase the speed of which your cursor moves compared to the mouse itself without messing with sensitivity, you'll need to play with the acceleration bar below the DPI setting. Higher DPI doesn't necessarily mean better performance, which is something you should note when looking for a new mouse.
I have anywhere between 15 DPI, even though this particular model (Naga Hex V1) can reach 5600 DPI. Going from low DPI to higher settings can cause issues in-game so be sure to spend some time getting acclimated to your new configuration. The higher this number, the more sensitive your mouse will be and the further the cursor will travel.
Sensitivity is determined by the level of DPI (Dots Per Inch) that are detected by the mouse and turned into cursor movement on-screen. The Performance area of Synapse will let you fine tune how the mouse tracks movement and whether or not you desire any cursor acceleration.
