A graphics accelerator assists graphics rendering by supplying primitives that it can execute concurrently with and more efficiently than the x86 CPU. One reason the accelerator can be more efficient than the CPU is because it lives closer to the graphics memory; it does not have to transfer raw pixel data over a slow (relative to the speed of the graphics RAM) general BUS and chipset. But the main reason a graphics accelerator improves overall graphics performance is because it executes concurrently with the CPU. This means that while the CPU is calculating the coordinates for the next set of graphics commands to issue, the graphics accelerator can be busy filling in the polygons for the current set of graphics commands. This dividing up of computation is often referred to as load balancing.