So, what was I doing right? I think it was mainly concentrating on my upper telltales. The wind was around 8 - 10 knots and I made a conscious effort on the beats and reaches to do everything I could to keep the upper telltales streaming, even if that meant some flutters in the lower ones. I adjusted the vang more than usual, experimenting a bit to see what it would do on the upper telltales.
One downside to concentrating on the upper telltales - or any telltales - is keeping your head inside the boat. And so it happened that after rounding a leeward mark, I was very efficiently keeping the telltales streaming just beautifully - as I started to head toward the wrong mark. Luckily I realized my mistake and managed to head the right way before too much damage was done.
Anyhow, I had consistently better boat speed than my friend. Was it the focus on the upper telltales? Did he just have a bad day?