Performance issue with setData and large content

[ckotzbauer]

Is this a bug report or feature request? (choose one)

🐞 Bug report

💻 Version of CKEditor

Current classic build (https://ckeditor.com/ckeditor-5/)

📋 Steps to reproduce

editor.setData(...) is very slow if called multiple times with a large document.
Use this gist for testing (anonymized real-world email) https://gist.github.com/code-chris/982dd128e5fe3eb58adaac5da947e0a1

1. Call editor.setData(...) with the above gist. This takes about 3-4 seconds.
2. Call setData again with the same content. This takes about 25-30 seconds.

Perf-dump when setData is directly called from the console

✅ Expected result

Calls with large contents are processed faster, even if there's already data in the editor.

❎ Actual result

All future-calls of the method are really slow and the browser hangs.

📃 Other details that might be useful

In our application this happens always if a user changes some data in the form (not only in the editor) and saves its changes. The save triggers a full data-reload which then calls setData again. This is maybe not ideal and we have to change this behavior in the future. However, the editor should not hang for about half a minute.

Maybe releated to #1041

[aschiffmann]

This jsfiddle reproduces the behavior: https://jsfiddle.net/Localhorstl/wjgm8xdr/

[oleq]

@code-chris @aschiffmann Thanks for the feedback! We're aware of some performance issues in the editor. We're tracking them all in https://github.com/ckeditor/ckeditor5-engine/issues/494. Please subscribe to stay updated.