With many tabs, adding a bookmark is slow

[ayumi]

Description

On a user profile which has 100 unique tabs, the time to bookmark a page via the toolbar bookmark star is significantly slower vs bookmark time on a fresh profile (~2000 ms vs 1000 ms)

Steps to Reproduce

Automated test (feature/perf-tests branch): https://github.com/brave/browser-laptop/pull/10517/files#diff-f741809427f0fd392187bcbcbef3ce44

1. Start Brave
2. Open 100 tabs each with unique URLs. (A quick way to do this is via Import bookmarks -> Bookmarks manager -> Right click a folder -> Open all in tabs)
3. Close Brave
4. Open Brave. It should remember the 100 tabs.
5. Navigate to a URL like example.com.
6. Click the bookmark star to add a bookmark, and see how long it takes.

Actual result:
Much slower with many tabs.

Expected result:
Similar speed to a fresh profile

Reproduces how often:
Always in the perf tests

Brave Version

master 29bdbd5

Reproducible on current live release:

Additional Information