<VV> Timing Question

[Joel McGregor]

I'll have to disagree here.  The optimal timing is also going to be the most efficient.
You will still have the same amount of fuel in the cylinder so the most power you can get from that charge will produce the best fuel economy.  If you advance or retard the timing from optimal you will get less power from the same amount of fuel which equates to worse mileage.
The car feeling snappier is very subjective and could just mean that the timing is better in the area you feel and not overall such as at cruise.  That would tell you that the static timing is possibly closer than it was but the timing at cruise with vacuum advance is further off than it was.