Motion or VR Sickness is a common problem which is caused by a mismatch of physical space and VR movement.
Performance refers to any frame drop or latency issues that may arise while using the headset.
Common problems may arise which negatively affect VR performance, a non-exhaustive list is found here.
System refers to the platform that your headset supports. For example, the Meta Quest 2 uses Oculus, but can use SteamVR if linked to a computer.
Do you have any physical disabilities relating to leg mobility?