I agree with Duke completely - East Short is a nice little course (though perhaps a bit too easy against the AI), but the second half of the full course does have a very odd pace/rhythm.
On the topic of this challenge... I rather like Infineon, but have had a devil of a time with the Corvette. After many tries a couple months ago I was able to breeze through the Cien mission (33?) and the three lap battle at Infineon, but still haven't passed 29. Probably about time to give it another dedicated session and see if I've improved at all.
Edit 8/24: So I didn't give it much of a go back in July, but came back to it a couple days ago - ran two tries and was still between .75 and a second off, but felt MUCH more in control of the vette and was hitting the right lines much better. Ran out of time that session, but went back to it yesterday and won it first time out. Wasn't anything tricky to it (so I don't have any useful feedback), just being a better driver, running Infineon more times in more cars, and getting some practice with faster, more precise cars (working on the GTWC).
Splits were +31.540, +14.400, -.248... not my best split at T1, but much better T1-T2. The last part of the course is just about positioning - if you're into third early enough to properly line up the fast right hander it's over - until my winning run I was always off the line on that curve trying to pass. With a clear run at it, you should pass into second before having to brake and line up the last turn.