Mail awfully slow when editing very long messages

[StCyr]

Steps to reproduce

1. Have a message with a lot of text (like 1000+ lines or 10.000+ characters);
2. Edit it (forward or reply to it);
3. Write some text

Expected behavior

Editing the mail should be swift

Actual behavior

Mail becomes slow to death

Mail app version

1.11.7

Mailserver or service

Self-hosted postfix/dovecot

Operating system

Debian 11

PHP engine version

PHP 7.4

Web server

Apache (supported)

Database

MariaDB

Additional info

No response

[StCyr]

Maybe caused by CKEditor => ckeditor/ckeditor5-vue#42

[StCyr]

2 observations from the ckeditor/ckeditor5-vue#42 issue:

1. The issue seems correlated with the number of top-level elements (see See also Very slow with large text ckeditor/ckeditor5-vue#42 (comment)). With Mail inserting lots of &nbsp when replying/forwarding a message, this could worsen the situation.

Excerpt of a message replied from Mail showing a single paragraph and the number of &nbsp elements inserted:

<p style="margin:0cm">&nbsp;<o:p></o:p></p>
<p style="margin:0cm">&nbsp;<o:p></o:p></p>
<p style="margin:0cm">&nbsp;<o:p></o:p></p>
<p style="margin:0cm">&nbsp;<o:p></o:p></p>
<p style="margin:0cm">&nbsp;<o:p></o:p></p>
<p style="margin:0cm">&nbsp;<o:p></o:p></p>
<p style="margin:0cm">&nbsp;<o:p></o:p></p>
<p style="margin:0cm">Some additional questions:<o:p></o:p></p>
<p style="margin:0cm">&nbsp;<o:p></o:p></p>
<p style="margin:0cm">&nbsp;<o:p></o:p></p>
<p style="margin:0cm">&nbsp;<o:p></o:p></p>

2. It seems the issue could be limited by adding some debouncing. See also Very slow with large text ckeditor/ckeditor5-vue#42 (comment)

[GretaD]

i tried this with different scenarios and its not happening anymore. We can open it again if its reported again. But for now i would close it.