Making an optimised concert crowd

Hi!

I'm making a phase in my game where there is a huge crowd (I tried something and got around 1500 people).
Those people are nothing more than GameObjects with a SkinnedMeshRenderer, an Animator, a CapsuleCollider and a Rigidbody.
The player will move across this crowd by pushing them around, so maybe they'll have a script attached to them.

But as expected it was running very slowly... I heard of ECS but it may not be usable in this case.
Does someone know a way of making a crowd like that so that it runs at 50 FPS or so please?