Check Mac's Activity Monitor. 1. How much CPU is Thunderbird using? 2. How much memory is Thunderbird using? 3. On memory tab, how much swap is shown at the bottom?

I've been unable to catch it in the act, yet. I'm now keeping Activity Monitor open always, to try to answer these questions…

I did not catch Thunderbird quite having the level of difficulty originally described. However, I did just have it acting with poor responsiveness. Activity Monitor showed it using 1.2GB of memory, with roughly 425MB of swap used. When I quit Thunderbird and immediately restarted, it came back using only 400MB of memory.

I'm not quite sure what to do with this information. Does it suggest a memory leak?

Is hardware acceleration enabled in Settings/General? If it is, disable it, restart TB, and see if typing improves.

I have now caught a peek at Activity Monitor while typing is loosing characters. It was using 70%+ of CPU continuously. The memory use was 900MB+. These are compared to a few % and around 350MB when freshly launched.

I have now turned off hardware acceleration, and will monitor. I should perhaps clarify that by "frequently" in my original question, I meant "frequently enough to be noticeable and annoying." As is likely clear from my responses since, I did not mean "every time I try to type something."

Hello. I have same problem with Thunderbird 115.3. Problem appears especially when I press "Shift"... maybe after dot as well, however I am not sure about it.

I disabled spell checking etc. Nothing helps. Sometimes even is printing keys which I press: eg. when I press "shift" thunderbird prints "shift", when I press Caps lock it print words" caps Lock" etc....

Weird.

Thanks Paweł Bobrowicz, it's nice to know that it isn't just me. Turning off hardware acceleration may(?) have helped for me. But it is very hard to measure "how bad" it is, so very hard to know whether it really got better. (Until it stops entirely, of course! :-)