23 minutes, why even worry about it? I would probably lolly-gag along at a leisurely pace if my commute were that short.

IMHO you really only need to worry about being faster when the commute is long and it takes upwards of 1 to 1.5 hours each way (like me). That's when it really starts to cut into family time, or time for other things if you don't live with a family.

Dang, 4 miles is nothing...