Formatting large content freezes the editor

[FilipTokarski]

📝 Provide detailed reproduction steps (if any)

1. Add some large content to editor ( I'm using the one from pagination demo )
2. Select all
3. Change font size/ apply bold / apply some other formatting

✔️ Expected result

Formatting happens immediately.

❌ Actual result

Editor freezes, sometimes for more than ~30 seconds:

📃 Other details

• Browser: Chrome, Firefox
• On Safari the freeze is almost unnoticeable
• CKEditor version: old issue, happens even on v15

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If you'd like to see this fixed sooner, add a 👍 reaction to this post.

[Mgsy]

Can you reproduce it also in the pagination demo? I've checked changing font size and it works as expected.

[FilipTokarski]

For me, it still freezes on export-pdf, export-word and pagination demos

[mlewand]

Same for me I can reproduce it on the default content of pagination demo https://ckeditor.com/docs/ckeditor5/23.1.0/features/pagination.html#demo

[Reinmar]

It seems that the post fixers are causing this again. It'd be good to check if this is related to our dear DocumentSelection#markers collection or something else. And if it's something else, whether there's some low-hanging fruit.

[Reinmar]

TODO:

• Check whether this is triggered by enabling pagination.
• Check this on latest master as we resolved the markers issue already.
• Check what's the origin of that (anonymous) that takes 90% of the time. Look for low hanging fruits.