Unity Game Optimization - Third Edition

Physics and time

Physics engines generally operate under the assumption that time advances by fixed values, and both of Unity's physics engines operate in this manner. Each of these iterations is known as a timestep. The physics engine will only resolve each timestep using precise values of time, which is independent of how much time it took to render the previous frame. This is known in Unity as the fixed update timestep, and it is set to a value of 20 milliseconds by default (50 updates per second).

It can be challenging to generate consistent results for collisions and forces between two different computers if a physics engine uses a variable timestep due to differences in architecture (in how floating-point values are represented) as ...