It seems there's something wrong with the GeForce 375.86 WHQL "Game Ready" drivers that were rolled out yesterday. Some users across the web are reporting this new NVIDIA driver release is plagued with significant performance and flickering issues. As such, it's probably recommended not to update your GeForce drivers until NVIDIA resolves this mess. At the moment, it's unclear which cards of configurations are affected.
The new drivers were supposed to be optimized for Battlefield 1, Civilization VI and The Division, but users who have downloaded the GeForce 375.86 WHQL drivers have identified a number of show-stopping bugs. Some gamers are experiencing heavy flickering inside of games, and not just the titles that were targeted by this release. Another, even bigger issue, is that for some players the GPU clocks now seem to be stuck at 810 Mhz, vastly decreasing performance in all aspects of use.
If you already installed the driver, the only way to resolve the issues is to roll back to an older driver.
Oddly enough, this is the second time in less than a month that NVIDIA's WHQL drivers are suffering from major issues. Last month's 375.57 release suffered from Windows Start Menu issues, screen tearing and pixelated images.