A modern graphics card’s driver software is vitally important when it comes to performance and features. For most applications, the drivers translate what the application wants to display on the screen into instructions that the graphics processor can use. The way the drivers translate these instructions is of paramount importance. Modern graphics processors do more than change single pixels at a time; they have sophisticated line and shape drawing capabilities, they can move large blocks of information around and a lot more besides. It is the driver’s job to decide on the most efficient way to use these graphics processor features, depending on what the application requires to be displayed.
In most cases, a separate driver is used for each resolution or colour depth. This means that, even taking into account the different overheads associated with different resolutions and colours, a graphics card can have markedly different performance at different resolutions, depending on how well a particular driver has been written and optimised.