As far as I know the driver is just the interface connection with a specific hardware. Why do I need to download new drivers when new games are released? How do they improve performance? What the hell is going on? I don't think nvidia is doing the usual PR for these games via drivers. Can someone explain to me why then they do it? And more... Why do drivers weigh so much? Almost 1GB. And a little more... Why do some games (let's say CS:GO) do you only have problems with video cards from a specific manufacturer (mmm AMD)? Let's say there are artifacts and so on.

Thanks.

1. The driver is an interface to the hardware, so it's not always perfect. New games (especially AAA cutting edge ones) use new GPU features which often require fixes to ensure they are working properly
2. Optimizations that help the game run better make it into the new driver. This happens by seeing the game in action and changing the way the driver communicates with the GPU.

Those are the big reasons.