Thunderbird (TB) hangs or is busy with something about 15 seconds, then it continues as usual. "Hanging" means here that it does not react to any click of mouse, but will recover from the hang situation after waiting a while (typically about 15 seconds). I have not found any explanation or logic for that hanging behaviour. Repeated hanging about 15 seconds now and then disturbs severely working. The hanging problem appeared at some point, not sure whether it is related to the update of version or something else. I installed manually older TB i.e. version 68.10.0 and defined one by one again about 20 mail accounts I have active (I monitor many systems and have email account for each). I was able to use it a day or two but today I saw message "upgrading" when I started TB and bang --- it had upgraded TB to version 78.14.0 without asking me anything --- and destroyed all the installation work I had done to test the older version instead. I have been using TB more than 10 years without any remarkable problems. Now this repeated arbitrary stalling a while is major annoyance. Client is Linux Mint. messages at terminal: (thunderbird:7414): GLib-GObject-WARNING **: 12:26:48.566: ../../../../gobject/gsignal.c:3493: signal name 'selection_changed' is invalid for instance '0x7f4734167fb0' of type 'MaiAtkType3' (thunderbird:7414): GLib-GObject-WARNING **: 12:26:50.673: ../../../../gobject/gsignal.c:3493: signal name 'selection_changed' is invalid for instance '0x7f4734167650' of type 'MaiAtkType3' (thunderbird:7414): GLib-GObject-WARNING **: 12:26:55.610: ../../../../gobject/gsignal.c:3493: signal name 'selection_changed' is invalid for instance '0x7f47367cf8d0' of type 'MaiAtkType3'