Unity 3D: Floating Origin Script (link in description)
https://gist.github.com/brihernandez/...
Floating origins are kind of a weapon of last resort when it comes to large worlds, but they're a problem that people repeatedly come across. There's a script for this on the Unity wiki, but it's a bit out of date so I updated it to work with more recent versions of Unity (2018.4 LTS) because they added scripting support for Trail and LineRenderers such that you can now make those work correctly with a floating origin.
I might make a full GitHub project out of this at some point. This isn't the most efficient thing I can think of, but it should work in the general case and isn't really noticeable in simpler scenes. This example has 2000 "asteroids" with Rigidbodies plus some particles/trails.