What I'm trying to say is - are you playing for the sake of playing or are you playing and trying to win?
Based on your response, I think you're shooting IDPA for the sake of shooting. I'll admit that this is a game, and when I play - I play to win. I choose the equipment that allows me to play the game best and that I am the most comfortable with. Perhaps you will get a better score going to some different equipment is what I'm suggesting, since your initial post adresses a concern about a performance peak.
Does your club publish a list of overall scores? Every club match I've attended does. It gives a stage by stage comparison of everybody against everybody. When trophy time comes, you wont be competing against SSP shooters but I think that once you start keeping score you're competing against everyone.
A failure drill is life-like, but IDPA is a game. As I said before, you have to ask yourself if you want to play the game just for trigger time, one example is failure drilling everything going slow - or to see how well you can do against others.
When you shoot IDPA, you are not just testing shooting ability. I believe you are testing the ability to play a game based on a fixed set of rules. Getting movers started is one thing that can better your score with practice. Generally speaking, there are many ways that someone can shoot a COF better than the way most shooters do it.
I believe that several things to improve your IDPA score is knowing how to reload and where (revolver reloads can be extremely slow when not using moon clips, even slower if its a reload with retention), what target to shoot first (when allowed), when to take extra shots are warranted, and how to read how a course plays out for other shooters so you can capitalize on where they encountered difficulty.