No problem

And by the way, as I've said before to others I personally cannot help out challengers with their projects, as that would seem unfair to the other challengers
But that rule is just for me, not for everyone else

HOWEVER when a generic question is posted here, then it's fair game!! hehe..

Anyhoo, the first thing that sprang into my mind when I heard about your issue:

1. FOR ALL OF YOUR DOMINOS:
In your geometry "Rigid Body" attributes in the Performance Rollout, set your
"Stand In" setting to "Cube" and set your "Apply Force At" setting to "boundingBox" for ALL of your dominoes.

You should be able to simply select them all and change the values in the channel box for all of them at once.
otherwise, the Attribute Spreadsheet is good for this as well.

If it is set to none, and the "ApplyForceAt" is set to verticesORCV's then the solving will take FOREVER as it is taking all of the extra unneeded geometry into account for the sim.

For dominoes, and most hard-bodied impact simulations, straight-up cube or sphere "stand-in" works SUPER fast and solves just as accurately for most cases.

Try that first and let us know if it helped your playback speed any

Also, keep in mind that if your scene has a LOT of geometry collisions, things WILL take longer to sim, and you may need to cache it first.


Ok, now for your second part:
How to speed-up a dynamic simulation.

The best and easiest way is to cache your sim, then select your geometry or particles, and make them a character in the Trax Editor

Once they are in the Trax Editor, you can simply lengthen or shorten your sim, or speed it up, or slow it down as well.

Check the help on using the Trax Editor.

Good luck!