Performance issues with large forms

Are you submitting a bug report or a feature request?

Bug report

What is the current behavior?

Forms with large amount of fields (>100, as is often the case with arrays and nested subforms) take a long time to render.

The slowdown is most notable on initial render, where the form can take up to 10s of seconds to render initially. Renders after that are usually fast enough, but not super-fast, causing some input delay.

If I run the Chrome devtools, I can see that the initial render slowdown is caused by notifySubscriber taking more and more time as more fields are being registered, making me think that notifySubscriber is not O(1) but O(fields already registered).

I’m building forms recursively from a JSON schema, maybe react-final-form is not the right tool for the job since all fields are know in advance, so I don’t need the notifySubscriber at all?

What is the expected behavior?

Speedy Gonzales!

Sandbox Link

I’ll try and put together an example soon!

What’s your environment?

final-form 4.6.1
final-form-arrays 1.0.4
react 16.3.2
react-final-form 3.4.2
react-final-form-arrays 1.0.4

Other information

See also #230.

Here’s a profile I’ve made with Google Chrome, you should be able to load that as well. profile.json.txt

[Dakkers]

Did George R.R. Martin write that pull request, by chance?

[Uznick]

@alirezavalizade any updates on that pull request? I’m facing this problem as well 😦