Yes, lap times are dominated by speed through, and out of, the corners, much more than in the straights, especially for novice drivers like us.
Just curious, Anchorman, why do you think more brake will help you? I read an interesting series of articles on DE driving awhile back, and the author made a convincing argument that in a DE, unlike in a door-to-door race where passing often occurs under braking, heavy braking going into turns is actually undesirable, as it upsets the balance of the car unnecessarily. He recommended started braking a little earlier, and more gradually. Personally, I've found that I have a tendency to over-brake, and my speeds have seen the greatest improvement from reducing my braking, and carrying the maximum amount of speed through the turns, so as to maximize exit speed. As Fangio once replied to a reporter's inquiry as to the secret of his success, "Less brake, more gas."
Another question - do you do your DEs on street tires, or racing compounds? I've stayed with street tires so far, but, as a result of the outstanding racing school I'm enrolled in (Driveway Austin), I'm in vastly better control of my car, and my smoothness has improved to the point where I think I can handle the more abrupt breakaway characteristic of racing tires. Just a matter of budget at this point...