I'm using a rigid body to move my character, it has a collider. So why does my player glitch through the walls specifically when it's going fast? My player is a capsule, I'm using a capsule collider. Is there any way to prevent this?
This is often caused by： When moving too fast, Unity misses the collision, since at a new timestep your player has already passed the collision area. A simple fix would to be either to enlarge your collider, shrink the model size, or to use continuous collision detection.
You can take a look at this Unity manual for more information. https://docs.unity3d.com/Manual/ContinuousCollisionDetection.html