I don't think anybody has addressed this yet but if you honestly have the base fitness (ie can easily ride double the distance and vertical of your group rides) and you don't have much weight to lose, work on getting more aggressive. That's what I've been doing. Note that everything after this is my very very short experience and is definitely not pro fit advice.

This means intensely stretching everything, every day. Twist your spine. REALLY stretch your hamstrings, especially after your rides. Do core workouts. Abs, obliques, even lower back. How long can you plank? How many sit-ups can you do? How good are your stabilizers? Can you balance on one leg with your knee at 60ish degrees? If you've done all this, and you think you can handle it, consider making your fit more aggressive to reflect your aggressive fitness. Drop your bars by one or two spacers. Get a saddle that allows for more hip roll. Tilt your saddle ever so slightly forward. Slide your saddle a bit forward (kind of like when you're on the rivet). Reconsider your saddle height. A higher seat means it's easier on your knees but it can mean a slower, less stable pedaling motion, less torque, and less hamstring and glute activation. There can be a huge dropoff with just a few mm too high of a saddle. If you're not feeling sore in your glutes and hams after a hard ride, you're leaving watts on the table.

Again, this is all from my short, personal experience. I would actually appreciate it if people could correct me if I'm wrong on any account because I'm trying to figure this stuff out myself.