hey nate, sounds like a great trip. I wish you luck.
when I hear race pace, I think minimalism. Cut out everything you do not need. for three days, thats alot you can lose.
If you really want to cut weight and increase mileage, comfort will not be a consideration.
I am not sure how you feel about hiking at night, but by adding a few ounces on a backup headlamp, you could drop over a pound on a sleeping bag by taking your rest during the warmth of the day, or the moderate temperatures in the evening. shelter then could also be made very simple: a rain jacket, and trash bag for your gear. Ridge rest pad cut to my torso length with my pack under my feet has always done me well for ground insulation.
I have always used aquamira or katadyn chlorine dioxide tablets. they are very easy, fast and light.
bring some duct tape, minor wound care kit (minimal). leukotape (for feet). some matches and esbit in a plastic bag for emergencies, nav. equipment. headlamp and a backup. rain gear. whatever insulating clothing you will need (minimal if you are moving at night and resting in the day) 2-3 pairs of socks. baby wipes. OP sack for food and large stuff sack (I usually hang this to keep small critters away) 2liters worth of water bottles. Gloves and beenie for night hiking. A backpack that is small and well balanced for fast moving.
that should be all you really need. maybe a small dropper of DEET and a whistle and mini knife for good measure, but that is just the boy scout in me.
for clothing: A pair of running shoes you trust and have broken in. some running shorts or compression shorts. a long sleeve polyester Shirt,( I like the ones with a zipper for ventilation) sun glasses, a alti/baro/compass watch. and wool or poly socks. ( I use smartwool, defeet and asics) Visor if you like.
you could get this kit really really light considering you are not carrying a sleeping bag, shelter, cooking gear.
its all in eliminating unecesary gear, some of the above items are not even really necessary.
for food, 3-4,000 calories should cut it. I also like bringing some sort of sports drink to mix with one of my water bottles.
check out andy skurka's food lists for his reccent treks, he manages to get alot of calories in a little weight.