I've been experiencing major Thunderbird freezes, which seem to coincide with the 91.8.1 release. I've gone as far as a complete reinstall of both Mint 20.3 and Thunderbird, and the problem persists. Steps to reproduce: Compose and attempt to send a message. Result: Thunderbird shows the 'sending message' dialog box, and stops. This will result in anything from a freeze that can sometimes be recovered from by force quitting (but only after several minutes, and I can't drop to a terminal to kill the process), to a complete system freeze that disables the power button, requiring removal of the laptop battery and disconnecting the charger. The freeze occurs using any of four email accounts that worked perfectly prior to introduction of the problem. The only fix I've found so far is to disable hardware acceleration. After doing this, I've been able to send a dozen or so test messages so far. Is this a known issue? I haven't seen a similar report, but I can't believe mine is the only machine affected.