The freezing is happening radomly, while writing, while searching, while reading. Also in previous versions of Windows 10 and Thunderbird.
THUNDERBIRD HANGS WINDOWS 10 HOW TO
NOTE: As a courtesy, we provide information about how to use certain third-party products, but we do not endorse or directly support third-party products and we are not responsible for the functions or reliability of such products. I am having this issue with temporarily freezing Thunderbird 60.6.1 under Windows 10 1809, too. Thunderbird will ask you for your password the first time you try to send mail.
THUNDERBIRD HANGS WINDOWS 10 INSTALL
Download and install Thunderbird if necessary. To configure Thunderbird with AlwaysUp: Download and install AlwaysUp, if necessary. Thunderbird is a popular, free, open-source email client created by the Mozilla Foundation.