It depends, running less than 90 fps is borderline and anything under 60 is a vomit comet. Most people have some issues with motion sickness at first but after a few days your brain adapts to it (so called “VR legs”). I regularly play games with lots of fast locomotion for 4+ hours at a time and have no nausea at all. Subnautica with an xbox controller in particular would send most people to the toilet after 60 seconds, which is a shame because it’s the most profound VR experience I’ve had.