(Photo: Tom Bojland and Ali Meller) A PHRF race on a very fast boat might not be very tactical, but a good fleet race amongst similar (one design) fast boats can be. I race 505s, usually considered a very high performance, fast dinghy (The F27 I blew over on a close reach the other day couldn't believe how much faster we were in those conditions). At the top of the fleet, everyone is going fast, and the racing is very tactical. The boats get a little more spread out than Snipes or J24s, but places are still changing all the way around. Having a wide range of fast angles to sail upwind (point high, or foot for speed), and a wide range of fast angles downwind (run at the mark, or sail high for speed), give more tactical options to pass or be passed. Things are happening more quickly too. So really it is a game of many more ways to attack, more ways to be attacked, and is happening rather more quickly. There is more to tactics than being inside at the leeward mark.
The priorities do change from class to class. In slow boats, being blanketed is not as bad, as the relative difference in speed is less. A fast boat has to spend more energy protecting clear air (that is still tactical). You also have to be fast enough to be playing the tactical game with the leaders. If you are off the pace, you are not in the game, whereas being off the pace is less of a problem in J24s or Snipes (my favorite examples of "equally slow" classes). Unlike multihulls we can tack very quickly (much faster than a J24), and we accelerate to full speed very quickly after the tack. This changes what is the best tactical move in some situations. If I were racing Snipes downwind, with a boat to starboard (both of us on port runs), and a gybe necessary for the leeward mark, I might gybe after the other boat and try for the inside overlap coming into the mark on starboard. In heavy air in a 505, I would probably try to gybe before them and go over them while they were gybing as clear air is more important. Once I take their air, they slow briefly, and I can work down in front of them, so I can still gybe at the mark without having to give them room. In either situation judging the best layline to the mark is key.
The Mix of Skills Differ in Heavy and Slow Boats
In terms of what you are concentrating on during the race, and how you divide your mental energies, I agree that this could differ boat-to-boat, but it also depends on a number of other factors.
When I frostbite in Interclubs, I spend less energy on tuning (but still concentrate hard on boatspeed), and tack for any excuse. Since the race has a very short beat, I play puffs and shifts and don't worry about persistant shifts. Since the Interclub does not go any faster when you foot, I will tack to clear my air, when I might consider footing briefly in a 505. I find that what I spend my thinking cycles on depends as much on the situtation and the weather conditions as on the class. If it is blowing a very steady 30, I do not spend a whole lot of time looking for small puffs, but I probably would when sailing in light and puffy conditions. The percentages of mental energy allocated to different aspects also depends where we are in the race and in the series, and how large the fleet is.