huge CPU spike on web.telegram.org

[fhoshino]

Description

Heavy CPU usage on latest brave release on telegram web without excess use.
Problem does not occur on 1.4.96.

Steps to Reproduce

1. Using telegram web (https://web.telegram.org/)

Actual result:

CPU usage constantly on 30% to 40%, spikes up to 50% to 60%.

Expected result:

CPU usage is around 10% to 20%

Reproduces how often:

Always reproduced.

Brave version (brave://version info)

Brave	1.5.112 Chromium: 80.0.3987.132 (Official Build) (64-bit)
Revision	fcea73228632975e052eb90fcf6cd1752d3b42b4-refs/branch-heads/3987@{#974}
OS	Windows 8.1 (Build 9600.19652)

Version/Channel Information:

On latest release only

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? No
• Does the issue resolve itself when disabling Brave Rewards? No
• Is the issue reproducible on the latest version of Chrome? No

Miscellaneous Information:

[rebron]

@kjozwiak to sign up for telegram and make new friends!

[bsclifton]

OK folks - we've done some investigation and are fairly sure we have found the root cause and the fix 😄 Build is happening now and we'll look at releasing a hotfix. Stay tuned 😄

[bsclifton]

@fhoshino (or others experiencing the issue) if you wanted to try a work-around while we're prepping the hotfix, here's what you can try:

1. Visit brave://flags/#brave-adblock-cosmetic-filtering
2. Enable this option
3. You'll be prompted to restart- go ahead and do that
4. Problem should be fixed 😄

[fhoshino]

Though this workaround seems fixing the idle hog, when loading stickers there is a much higher CPU usage when compared to 1.4
Before it might be using up to 50% total CPU, now it is up to 70% of total CPU.

[kjozwiak]

Going to use #8779 as the main issue that QA will use to verify that brave/brave-core#4999 fixed the problem. We'll also use the same issue for the release notes once we push the 1.5.x in a few hours.