Scalability: Prevent EF from loading every author all at once

[WPprodigy]

Extracting an issue that arose in #265

There are two places where Edit Flow will load every author+ (editor & admins included) all at once, which could present scaling issue on a site with a very large amount of users with author capabilities.

As a side note - It's worth noting that WP core will also load every author+ for the core author metabox. This ends up being one giant select field. I'm thinking there could possibly be some value here for EF to perhaps unset the core metabox and register it's own, perhaps using part of the solution used to solve this issue.

The two places where EF currently loads all users are:

1. On every post/page's notifications meta box:
   

2. When editing a group:
   

From @sboisvert:

I could see a hybrid model where we show all authors if the count is less then X where X is filterable with a default of let's say 20 [totally arbitrary number] and then if you want more you need to search. Maybe in the UI we'd put a note at the bottom of the list that mentions that you need to search to get more results. This should allow us to have the inline disabled button. That being said, I might be overthinking it and Ajax is the way to go.

I'm also thinking it will be important that all currently subscribed/selected users are always loaded and shown at the top. As a part of implementing this, the All and Selected filter logic and UI could likely be done away with.

[indralukmana]

Hi I am interested in working an enhancement for this issue.

I am wondering if something like a “more” button will be useful for this issue. So the flow will be: some small subset of the authors loaded first and then additional authors can be loaded using “more” button.

One other idea I have in mind is splitting/paging the authors alphabetically.

How does these idea sounds for the issue?

[indralukmana]

Scratched the idea in the previous comment. Now working on users list pagination with Ajax.