Brave Extension increases page load times by ×10

[da2x]

Steps to Reproduce

1. Visit a very simple HTML page like https://example.com
2. Open Developer Tools: Performance
3. Click record page load time.
4. Focus in on the page load portion and inspect what’s slowing down the page load.

(Compare to Edge or Chrome with no extensions.)

Actual result:

content_cosmetic.bundle.js (a script inserted by the bundled Brave Extension) increases the page load time by ×10.

Even for simple pages, page loads go from 30–50 ms to 500–700 ms. (Times excluding networking overhead.)

For more complex pages served from a local file (no network overhead), the Lighthouse performance score drops from 98 to low 60s.

Expected result:

No compromises on performance. (Or, at least only tiny ones.)

Reproduces how often:

Every time.

Brave version (brave://version info)

1.28.105 Chromium: 92.0.4515.13

Version/Channel Information:

stable

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, it’s Brave specific.

[bsclifton]

cc: @antonok-edm

[antonok-edm]

@da2x I'm not able to reproduce your issue. I do see some overhead, but certainly not 10x.

For comparison, I get 74ms for Scripting when running with Shields disabled.

If you're seeing 500-700ms then something definitely sounds wrong, but I'll need more information to look into it further.

[da2x]

I get the same result on my much faster gaming desktop computer, but I get 500–700 ms on my Lenovo laptop from 2018. I can reproduce it on my desktop by throttling the processor. Intel i5 7200U with relatively slow 1GHz RAM.

[Tonev]

@bsclifton @antonok-edm

Related to #17906?

[antonok-edm]

@Tonev possibly. It would also be good to check if it's affected at all by brave/brave-core#9995

[atuchin-m]

To resolve this the following issues should be done:

• Remove extension-based cosmetic filtering backend #17918
• Optimize parseDomain in content_cosmetic.ts #17906
• Optimize multiple initializations of content_cosmetics.bundle.js during frame load #17935

[iefremov]

@da2x we significantly optimized Brave Extension in Nightly, would be great if you could test that.

[iefremov]

Pls reopen if this happens again