Rated 4 out of 5 stars

Thunderbird freeze on initial sync with Google People API, not recovering. 4600 contacts, 60 groups.
On google API console only very brief connection, thread eats whole CPU core but seems not connecting to Google API.

This review is for a previous version of the add-on (0.3.0). 

Thanks for Your review.

For Your issues, please open specific tickets on GitHub, so I can better handle them.
The first however is a well-known one. Until a newly-written version comes out, You can mitigate the situation by unchecking the "Include system groups" flag.

MZ