Hi,
I recently hit a performance issue with a liveview form.

The structure the form edits has lots of association handled dynamically using cast_assoc.
Everything works fine for ~70% of the cases (with just a few assocs), but the 30 remaining percents can have more 100, 200 assocs and the users struggle a lot. In this kind of cases, websocket frames can be 30, 40 KB on each validation.

Just to give a feel of what the form does (and simplify things), let’s imagine it allows to edit staff in a movie :

movie (with a few specific fields, like title, length...)
  -> has many professions (10+, must validate uniqueness in movie and not empty, with a few specific fields) 
       -> has many people (100+, must validate uniqueness in profression and not empty, with a few specific fields)

people are managed somewhere else, i just create a drop down so they can pick a person and add a few metadata for this peculiar profession 

To stay in the example, most of my users manage indie movies with less than 40 people and everything works well, the issue are the blockbusters (and the UI should be able to handle both, so keep everything in a single page without modals or tabs or navigation because for most of my users the form is not that big. )

Do you have any advices about how to handle this ?
Best,
Matthieu