Downgraded from Thunderbird 1xx to 91.11.0; lost Address Book and saved emails

That is to be expected.

you do realise there is a profile export in the 102 version that would have exported your profile for use elsewhere I hope.

Personally I doubt hanging issues are related to V102.2.1, but basically windows 7 is used by very few, so nothing is certain.

Generally issues with freezing on windows 7 come down to a couple of things. Antivirus products. These can cripple a system, especially if the profile is large and has large files. Every ten minutes you get new mail and the A/V starts scanning the mail store file over again. Unfortunately if the store is large it may well have not completed the last scan. So you never actually get unencumbered access to your store.

Slow or "sick" hard drive. For this you need to use he windows disk utilities to scan the disk for errors. (generally on older systems you have to restart once you ask for the scan so it can complete. Using to defrag utility is also a good way to speed up an older system using a platter type drive.

Lack of memory. As time passes the memory requirement of everything explode. Older systems rarely have sufficient memory to effectively multitask. The system requirement published for Thunderbird are something of a joke. Those limits are barely enough for the program to start, let alone actually function well.

First Find your profile, backup your profile, then remove the .bak extension from address book files. https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data

When you start thunderbird, you will need to use -P --allow-downgrade to pick your profile and allow the older version to access it.