Help Managing thousands of objects

[ImpossibleRob]

I have a game where the user can place many objects, potentially thousands, and also use a couple of ropes which should then react to these. The issue is, the ObiUpdater becomes incredibly slow looping through all the obi colliders and updating them. It reaches easily 500ms for only 4000 objects on a high-end pc per frame. 

What are recommendations to handle such scenes? Are there optimization tricks or settings I can tweak?