Editing codeblocks with > 30k lines is slow in Chromium

[max-nextcloud]

Steps to reproduce:

• visit prosemirror.net with Chromium (/Chrome)
• insert a code block
• paste a large document with many lines such as the first 40k lines from /usr/share/dict/american-english
• start typing somewhere in the codeblock
• if you type fairly fast CPU will start spinning up and text will only be inserted after stopping to type.

If you have a fast computer you might need to paste more text. Observed this on a Intel(R) Core(TM) i7-7600U CPU @ 2.80GHz.

Firefox seems fine from what i could observe.

Why would one have a 40k line long code block? In @nextcloud/text we are using code blocks to render the content of plain text files and code files. People are complaining about this in particular in the context of opening log files that can easily be much larger.

[marijnh]

How responsive is editing the same document as a plain contentEditable element?

[max-nextcloud]

Oh my... you are right. It's already slow when opening a plain contentEditable from a plain html file.

[max-nextcloud]

I seems to become more responsive when splitting the single <pre><code></code></pre> block into multiple separate code blocks.

@marijnh I guess working around such a performance issue in chrome is outside of the scope of prosemirror - or what do you think?

[marijnh]

Yes, I do indeed consider this out of scope. If someone finds a low-impact kludge that could help here I'd be interested in taking a look, but as a rule, the library doesn't take responsibility for browser performance issues.