Prerequisites

• I verified that this is not a filter list issue. Report any issues with filter lists or broken website functionality in the uAssets issue tracker.
• This is NOT a YouTube, Facebook or Twitch report. These sites MUST be reported by clicking their respective links.
• This is not a support issue or a question. For support, questions, or help, visit /r/uBlockOrigin.
• I performed a cursory search of the issue tracker to avoid opening a duplicate issue.
• The issue is not present after disabling uBO in the browser.
• I checked the documentation to understand that the issue I am reporting is not normal behavior.

I tried to reproduce the issue when...

• uBO is the only extension.
• uBO uses default lists and settings.
• using a new, unmodified browser profile.

Description

I have a similar problem with #3724 but I’m not completely sure if "no-large-media" is the cause because there is no console log/spam. After I open the browser and visit a few sites, about 30 seconds later the network completely locks up, no connections work at all until I either close the browser or turn off uBlock.

On top of that, once the freeze happens, the browser task manager shows uBlock using %100 of the CPU.

I can’t capture a log for this because the uBlock's extension settings section becomes completely unresponsive, none of its tabs/pages will open. I can’t even click on the uBlock extension icon in the top right corner of the browser.

Browser: Opera 120.0.5543.161
uBlock 1.66.0 from the Chrome Store (broken)
uBlock 1.65.0 from the Opera Store (works fine)

A specific URL where the issue occurs.

Exactly everywhere but,
https://www.youtube.com
https://x.com/home
https://mail.google.com/mail/u/1/?tab=wm&ogbl

Steps to Reproduce

1. Open browser with uBlock enabled
2. Browse and switch between sites such as X/Twitter, YouTube, and Gmail.
3. After a short while like 30sec, the browser network becomes blocked.
4. At this point, no new connections work until you either close the browser or disable uBlock.

Expected behavior

Issue should not be occurred

Actual behavior

No new connections work until you either close the browser or disable uBlock.
The uBlock's extension page and extension icon also become unresponsive.

uBO version

uBlock 1.66.0

Browser name and version

Opera 120.0.5543.161 & 122.0.5643.17

Operating System and version

Windows 11 24H2(26100.4946)