On two of the 24 launch titles, we actually saw performance drop with the new feature enabled.
Nvidia’s new Variable Rate Supersampling (VRSS), which launched in a driver update during CES 2020, promises high-quality antialiasing in VR games with less of a performance hit than traditional Multisample anti-aliasing.
…It does not require any input from developers as it is a driver-supported shading technique that can be applied to any DX11-based VR game or application that uses Forward Rendering and has support for MSAA.
Source: Tested: Nvidia’s Variable Rate Supersampling Doesn’t Deliver on its Promises (Yet) | Tom’s Hardware