Performance/web-compat issues on YT page

[Uni-verse]

Description:

Performance issues on YT page sometimes, its more obvious if using playlist feature. Adding videos to playlist, opening them in playlist and returning to the YT page will result in the UI being unresponsive or laggy.

Doesn't happen when shields are disabled.

Steps to Reproduce

1. Install 1.52 (23.6.28.13)
2. Open new tab, navigate to youtube.com
3. Load a video, add to playlist
4. Tap on playlist icon and select Open in Playlist
5. Close playlist, return to YT video page
6. Try to pause/play video or scroll through related videos
7. Repeat several times, try to add more videos to playlist.

Actual result:

RPReplay_Final1687976177.MP4

Expected result:

Page should load successfully, UI should be responsive

Reproduces how often: [Easily reproduced, Intermittent Issue]

Intermittent

Brave Version: 1.52 (23.6.28.13)

• Can you reproduce this issue with the most recent build from TestFlight? Yes
• Can you reproduce this issue with the previous version of the current build from TestFlight? No
• Can you reproduce this issue with the current build from AppStore? No

Device details:

iPhone, iOS 16.3.1
iPad, iPadOS 15.5

Website problems only:

• did you check with Brave Shields down? Not reproducible when disabling shields
• did you check in Safari/Firefox (WkWebView-based browsers)?

Additional Information

[Uni-verse]

Verified on iPad (9th Gen) running iPadOS 15.6.1 & iPhone X running iOS 16.5.1 using version 1.52 (23.7.3.17)

• Ensured that navigating youtube.com does not cause page to freeze or fail to load content
• Ensured added videos and opening playlist works
• Ensured ad blocking is working for normal and aggressive ad-blocking modes