@morlig - Thanks for getting back to us with an update!
Even with the choice_filter, I’m not too surprised that it takes so long to load 16k choices.
What version of CHT are you running? If you’re back on CHT 3.x, there’s some amazing speed improvements done in CHT 4.x - and when CHT 4.6 comes out, it will ship with an updated Enketo version which should specifically make your use case faster.
That said, assuming we see a 2x speed improvement, I suspect 2.5min is still too long for a form to load. I would suggest breaking up your workflow so that the user is never selecting from more than 100s of choices.
If you do the work to break up your workflow like this, it would be great to hear back on your results! I’m sure there’s some interesting thresholds the CHT will hit where it starts to really slow down.
Finally - If it is appropriate to share, what is the workflow you’re using the CHT for that has 16k choices?