User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:89.0) Gecko/20100101 Firefox/89.0

Steps to reproduce:

• Navigate to several webpages
• Open the history tab (ctrl/cmd+y)
• Select 10k individual entries (or more)
• Delete them

Actual results:

While the entries are being deleted, the browser becomes unusable. Windows do not respond to user input, video playback ends, context menu and webpages do not react to input. Once the entries have finished, control is returned to the user.

Expected results:

While the entries are being deleted, the browser should be usable as normal.

The Bugbug bot thinks this bug should belong to the 'Firefox::Bookmarks & History' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Thank you for the report, this is a known issue. Some improvements to the overall delay time have been made recently, and we are hoping to make more soon.