Uhh it should be the other way around; using a tight setup at Richmond oughta make you slow the first 40 laps, but you'll be more and more competitive as the race goes on, the more so with the weather you had in your race (cloudy 57°F). This is because the car gets looser when the tires wear, not quite as bad as at Phoenix for example but yet very noticeable.
You can actually be very fast at Richmond without being too hard on tires, only about a tenth over hot lapping pace, if you've figured out how to drive this track smoothly. This was probably not the case though judging by the lap times, I reckon that it would be possible to hit 20.8s in qual trim and 20.9s/21.0s running hard in race trim at these conditions.