Hi, I've noticed my TB78 did not get a prompt to update for a very long time, but today it did prompt to update to TB91 when I checked Help > About. So I did the update and everything seemed fine, until I went into the Options pages and everything started hanging, it was impossible to click anything and the UI was not responding. Eventually I looked in Process Explorer and saw the main Thunderbird.exe process memory use (private bytes) rising massively, to several GBs within the scope of seconds. It got to maybe 12-13GB and I started to worry about a system crash so I terminated it. I tried creating a new profile and launching it, and it seems fine there but obviously no accounts set up. I also disabled all add-ons without it helping. I have now restored TB78 + profiles from a backup and it works again. So what can I do to figure out what's causing this massive memory leak and hang issue? Also is there a simple way to migrate the old profile to the new one without having to create all accounts again? I have several Local Folders in MBX format I would need to migrate over as well, and the import "wizard" does not give the option to import from another TB profile (far as I can tell...) OS: Windows 10 x64 21H1 Processor Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz, 4001 Mhz, 4 Core(s), 8 Logical Processor(s) Installed Physical Memory (RAM) 16,0 GB Available Physical Memory 13,6 GB Adapter Description NVIDIA GeForce GTX 970