Forgot to do liquids. APIC. By the way, version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: rB02948a2cab44

Create two cubes. The domain is 25cm25cm50cm at 0X 0Y 15cmZ and the cube is 10cm10cm10cm at 0X 0Y 0Z. Everything is default expect for the timestepping.

Can't believe I didn't think of this. Here are some tests of 2400 fps simulations with no timestepping, the temporal equivalence of 24 fps and 100 timestepping.
Smoke, 64 domain, 2400fps edited to real-time. Looks exactly like 24fps with 100 timestepping:

D5797#237065 comment section?

David's original scene Comptest Chain.blend (6mb) used three separate cubes each with a convex hull. This one works.

It's a limitation.

The "issue" that I had was that the size of the simulation was too small for the timestep size. Normal 50 in meter sized sims works fine:

I found the issue. Collision sources Final and Deform don't work (as expected) but Base does.

With respect to particles, initial velocity source does change the simulation, but at an imperceptible level compared to using meshes.

It's called narrow band

Here I compare between 0 and 100 (max) for the initial velocity. There's very little difference in using the maximum value.

version: 2.92.0 Alpha, branch: master, commit date: 2020-12-20 17:48, hash: d283a093d664

Turn "Single Sided" off in the collision settings

Blender's rigid body documentation is useless. But when you learn how to use it:

I had no issues

You are doing something wrong, I ran into no issues.

The September 7 dev notes mentioned an update to the Bullet library. I downloaded b351607996e4 and the issue wasn't there. Every primitive can be used now! The last thing to make rigid bodies perfect is resolving the need to enable a collision margin of 0m to fix some interactions, but I can wait for that.

Should have added that in the instructions, capsules push each other slightly while other primitives don't.

2.83
I too have encountered this problem.
Some testing I did:
1 rigid to 50 objs = 0m:16s
1 rigid to 100 objs = 0m:33s
1 rigid to 150 objs = 0m:49s
1 rigid to 200 objs = 1m:07s
1 rigid to 250 objs = 1m:23s
1 rigid to 500 objs = 2m:58s
1 rigid to 1000 objs = 5m:52s
1 rigid to 2000 objs = 12m:02s
1 rigid to 5000 objs = 36m:52s