Indexing Broken in Windows 11 (Painfully Slow At Best)

Hello

I have upgraded to Windows 11 Pro on two different laptops, and both have the same issue with indexing. It is painfully slow and then usually resets itself after a couple of weeks.

Both PCs are high-end laptops with Core i9 mobile CPUs (1 x 6 core and the other 8 core). Both run 2 x NVMe 1TB drives. Both have 64GB RAM.

Both run MS Office and I use Outlook for email connected to same IMAP accounts on both. My docs, pics, music and work-related files are all stored on OneDrive and accessed from both PCs (OneDrive is set to keep local copies on both PCs for fast access).

Windows is being asked to index around 250,000 files and 80,000 emails and calendar appts. Windows 10 used to accomplish this task in 6-8 hours max.

Windows 11 takes nearly two days just to index the emails. It can take up to three weeks to index the lot and then some folders simply refuse to be indexed. Then, after a couple more weeks it will eventually lose the lot and indexing has to start from scratch again (on both PCs)

I have tried:

Disabling backoff via registry so indexing never pauses

Only adding one location at a time to let it slowly build up (e.g., add only Outlook and when that finishes add a folder)

Rebuilding the index

Storing the index in different location

Search and Indexing Trouble-shooter

Nothing fixes the issue

Any help appreciated.

Cheers

Mick