For a smooth and immersive VR experience, a minimum of 90 frames per second (FPS) is generally required in most VR applications and games. Anything below this can result in motion sickness, eye strain, and a less realistic experience.
Some high-end VR headsets such as the Valve Index and HTC Vive Pro can achieve even higher refresh rates of 120 or 144 FPS, which can provide an even smoother and more immersive VR experience.