Temporarily freezes some release pages

[jesus2099]

I don't understand why it freezes these two particular release pages.

• https://musicbrainz.org/release/ef258ef2-132e-4085-8c2a-5b053a0632cd
• https://musicbrainz.org/release/5ccc805d-8cd1-4199-8420-f54321429289

They have the same artist, so it's because of something in the artist open edits.

In fact, any of the pages for Mohsen Namjoo will have this freeze, including simply the artist page itself.

But there are only 64 open edits, which is far less than Various Artists 500+ edits with no freezes on any of my VA releases.

[jesus2099]

I quickly used Performance tab in Vivaldi dev tools for the first time and it tells me that almost all of CPU is taken by some /[^<>]+(?=<\/bdi><\/a><\/h2>)/g regular expression:

konami-command/mb_PENDING-EDITS.user.js

Line 148 in e4aa0f8

types: this.responseText.match(/[^<>]+(?=<\/bdi><\/a><\/h2>)/g),

[jesus2099]

In https://regexr.com I try this /[^<>]+(?=<\/bdi><\/a><\/h2>)/g regular expression on Open Edits for Mohsen Namjoo source code and it tells me:

EXEC RROR: The expression took more than 250ms to execute.

When I try same thing on Open Edits for Various Artists source code, it executes fine and finds 100 matches in 35.3ms.

[jesus2099]

The VA open edits source code is bigger in size… 🤔
I try zero space positive look behind in addition to my zero space positive look ahead to see if it improves performance: /(?<=<bdi>)[^<>]+(?=<\/bdi><\/a><\/h2>)/
It's acting better in EmEditor but It does not seem to be supported by Vivaldi…

[jesus2099]

I came up with /<h2><a href="[^"]+"><bdi>([^<]+)<\/bdi><\/a><\/h2>/ the fastest regular expression for what I want in RexExr but it requires some changes in my script to retrieve the grouped value, now that I don't use the zero width positive look ahead no more (which seemed to be the CPU heavy demanding feature).

• Mohsen Namjoo is scanned in 1.2ms instead of very long time
• Various Artists is scanned in 1.6ms instead of 35.3ms!