If it's supposed to be a classic tower stacking game, why don't you disable physics once the object has been placed?
There's no need to further simulate physics with hundreds of stacked sprites, especially not for those outside of view.
I would suggest:
On collision -> wait till somewhat stabilized -> disable physics if stable
So the next one falling down has a flat surface to work with.
Unless that's your intent of simulating everything with accurate physics.
However that's gonna be a tough one.
Some hybrid physics might be better to simulate a long wiggly stick based on current height.