Why does Nav Mesh Run Slower in build mode than in Editor?

So I’ve made some little enemies that use Nav Mesh to chase the player. I tweaked their speed on the nav mesh agent in the editor to get it just right. When I built and ran the project though, the enemies appeared to be moving a lot slower, and also turning very slowly. They must be at least half the speed, possibly more, both movement and turning.

Also, nothing else seems to be running slower in build mode, just the nav mesh agents. My other code to make them turn to face you when they are close is just as responsive, and the players movement seems the same.

I can’t see that it’s meant to be that way - if it’s unavoidable, it’s gonna make testing a lot slower.

Has anyone else noticed this happening before? I’m using Unity 20171.0f3, incase it’s a bug. And I have to keep using that version because that’s what College has at the moment.

I worked out it was because of Rigid body interpolation being turned on.