Not responding, connectivity issues, slow deleting

If this is an IMAP account, everything you described can be attributed to network problems. Either that, or a VPN or firewall or antivirus interfering with the mail. Thunderbird does not cause such as this.

Same problem for me. I do not use VPN, I did not changed my antivirus Microsoft Defender and it does not report any problem. My network works correctly with other mail servers i.e outlook.

I checked everything too. What's your ISP?

After having save my profile and unstalling I reinstalled the proposed version for unloading which appeared to be ESR version a higher version than the basic one which cannot read my saved profile. I had to let my computer to a specialist who got from Thunderbird the way to render readable my profile. When previously checking my PC system he corrected some problems in FAT and eliminated five virus.

However the problem re-apeared when I introduced the password for account @yahoo.fr and I have to remove all the imap.yahoo.fr from my profile to be able to run properly TB with my other account. It was done following the instructions done by copilot. Copilot also explained me the reason of the crash which is well reported on the web since 2024. It is due to Yahoo which for security reasons alway accept the passwords generated by the application. See copilot for further details.