Try a little trick on the sections that are stumping you:

Take some masking tape and cover the speedo and tach. Now go ride the area that bothers you and stop worrying about the numbers. Go relax and ride the sections multiple times, varying line and entrance exits. Let the bike move around under you without consciously trying to increase speed.

Like anything else in this game, speed is a function of comfort, familiarity and technical variance, that comes as a result of practice, a willingness to learn and seat time. Go direct some seat time at the ares bothering you, but do it slowly.....speed, smoothness and comfort will be the natural result.....pushing speed only usually results in crashing..................