Found it!  The relationship between the size of the bleed hole (on the
damper pneumatic or any pneumatic on any piano) and the resistance to
air flow can is described by the Hagen-Poiseuille equation:

        R = (8 * L * n) / (pi * r^4 )

where:  R is resistance to flow
        n is viscosity
        r is conduit radius
        L is the length of the conduit

Doubling the radius decreases the flow resistance by a factor of 16.
This relates to Craig Brougher's suggestion to enlarge a bleed hole as
a possible solution to the slow recovery time of the damper pneumatic.
But how much?  A 25% increase in the bleed hole size decreased the flow
resistance (increased the flow volume) by a factor of about 2-1/2
times.

My doctor told me the same phenomenon was keeping me from breathing
well at night and the correction was to remove a little spur from my
deviated septum.  He also told me that very little would have to be
removed due to the fourth power relationship of the flow resistance
to the orifice size.  That was about 8 years ago and I've been sleeping
like a baby since.

Larry Toto