I'm curious, had you written a generic version, would you still be ripping the code out? (I'm guessing so, otherwise presumably you would now be making that code generic).

I still find it funny that the place to optimize is generally for 'rip-out-and-replace', rather than 'extend' (caveat emport, not always the case, but seems to be a better design to optimize for replaceable than it is to optimize for abstract & extensible)

We built to the wrong abstraction. We had a choice of two optimisation variables that were conjugates (i.e. you can convert from one to the other like frequency/time, momentum/position etc). We chose the one that was simpler to implement, it turns out the other one is actually more expressive and useful for our purposes.