Operating system: win 10 pro
Graphics card: 1070, driver : 126.96.36.1995
ram 32gb ddr4
processor i7 7700k
slow physics calculation in scene with lots of scattered objects (hair particle system foliage).
I can't share the file as it's a client file, but basically I have a scene with lots of scattered foliage using hair particle systems (no dynamics), and some high poly geometry (not scattered). I've added a tank to the scene, and have set up the tracks to be driven by mesh cogs using physics (see this tutorial if you want to recreate https://www.youtube.com/watch?v=q5fjslhomsI&t=234s).
The problem is that even though I only have the layer visible which has the tracks and wheels, and there's nothing else in the scene which has physics/dynamic, the physics calculation is exceptionally slow (1fps), however if I copy the tracks and wheels to a new file, then the physics is calculated at 60fps with the same settings...even if the other file is still open (indicating not a system resource issue)