If you are on Windows, using the most recent version of Thunderbird 128.6.x or 128.7.x, ... * Start Windows in safe mode with networking enabled - https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode * Still In Windows safe mode, start Thunderbird in Troubleshoot Mode - https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird Does problem change? If it did not improve, please create a profile using https://support.mozilla.org/en-US/kb/profiling-thunderbird-performance