Rated 4 out of 5 stars

This addon freezes thunderbird all the time. It also freezes many other windoze apps too when thunderbird is frozen that use the same subroutines. Suggest using it, then disabling it, and only enable/use when you need to sync manually.

Update: Gsync isn't why TB is freezing. Will continue investigation: thanks for replying Josh!

This review is for a previous version of the add-on (2.0.11). 

If it freezes while synchronizing I suggest making a new address book and setting up sync with it to see if it syncs more quickly. The Mork DB format used by the TB address book seems to degrade and perform very poorly sometimes, though I can never seem to recreate the problem.

If you don't want to do that you can at turn off automatic synchronization in the gContactSync preferences instead of disabling/enabling and restarting Thunderbird.

Josh