This is how I resolved the issue where Lightroom Classic (LrC) took about 13 minutes to complete a Catalog backup. A big increase from about 2 minutes.

My Catalog, as of Feb. 2023, is 1.47 GB containing about 59,000 photographs.

Prerequisites

• Make sure Adobe Lightroom Classic is up to date.
• Configure Lightroom Classic to back up the catalog on exit
  1. Choose Edit > Catalog Settings (Windows) or Lightroom Classic > Catalog Settings (Mac OS)
  2. Set “Back up catalog” to “Every time Lightroom exits”
  3. Click Ok
• Exit from Lightroom Classic
• Backup the Catalog when prompted

Invoke “Test integrity of this catalog” on Lightroom startup

1. Display the Select a Catalog dialog starting Lightroom by holding down the Alt key (Win) or Opt key (macOS) while starting Lightroom
2. The problem Catalog should be selected. If it is not, then click on the Catalog you want to work on.
3. Tick the “Test integrity of this catalog” check-box
4. Click “Open”
5. Quit Lightroom, without backing up. Click “Skip This Time”
6. Open Lightroom normally.
7. Quit Lightroom, backing up with the “Test integrity before backing up” and “Optimize catalog after backing up” boxes ticked.

After completing the above steps, the Catalog backup completed in about 2 minutes. Down from 12-13 minutes.

Environment

Program:	Lightroom Classic r12.1
OS	Windows 10 Pro v22H2
Workaround	2023-02-10