Main Features:
(1)
Adjusting AI lines to be safer(mostly corner exits) so that bots don't drive outside so often. Doesn't fix human errors from lap, like driving offroad or hitting obstacles so only use Lap Improver with "clean" laps(corner cutting should be ok, at least in theory). Also remember that final time that program gives out is just a target, bots won't be able to reach that.
(2)
Improving AI lines for some corners if it is possible to do(safely). Doesn't do that much for very good laps but average ones usually benefit.