believe me you are wrong about the AI slowing down too much... in the current state without modding it's almost true, I have done dozens of mods for cars and tracks in AC which I've never published here or racedepartment or anywere else, because those tracks and cars aren't mine, but if somebody will ask me... I can upload here lots of stuff that literally transforms AC into a better AI experience! I've remade AI pathes for almost every track in AC and believe me since version 1.1 the ai overtakes each other much more effectively and frequently, it brakes later and drives like a charm!
you have only to rewrite AI pathes for every track (if you are able to) and that will make them faster and more effective! some of them need more aggression, but u can change it via AI.ini file or in the AI app during the game (I recommend to do it that way only in order you can actually observe in real time how they behave).
p.s. I wonder why kunos didn't to it already with their 1.1 update for the default tracks...
for any info please, PM me! ;-)