Awful performance with many non-physics entities about bevy_xpbd HOT 3 OPEN

Hi, I am also seeing poor performance with colliders. In my case I do have many many colliders at a time, but when I scale down I do not see the expected performance improvement.

Is it possible to further parallelize collect_collisions? When I run a trace, I see the initialization run in a task pool but collect_collisions always appears in the main thread (I suppose Bevy/Rayon could be deciding this is best). I see it is using par_splat_map but for some reason it is not chopping up chunks into threads for me--it does it all at once in the main thread.
I was not tracing properly.

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Another thing I found: If I spawn a bunch of colliders, check some collisions, and remove layer filters until the only remaining filters are ones without any collider memberships, then I don't get any performance back. The performance indicates that it calculates the same collisions regardless of filters.

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Another idea (from Rapier): there should be an option to skip computing contact points (just collisions) for some colliders (i.e. sensors). It would also be a nice optimization to skip recomputing collisions if at least one of the objects is a sensor and has not moved since the last computation.

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