A few months ago, Thunderbird started taking 20 to 30 seconds to check the mail in my main account. I have identical settings (except for the email address portion preceding "@") on a secondary account, which takes only two or three seconds to check email, as always. I had about 25,000 messages in the main account inbox. I moved the oldest half of them to a local folder and compacted the Inbox. As expected, that had no effect. I have let my inbox grow to over 50,000 messages before the slowdown occurred. I'm using POP3, Port 995, SSL/TLS, leaving messages on server, authentication method Normal Password. I'm specifying the server by its actual box name, not with "mail" in the name. Automatically download new messages is checked. I tried to get help from my ISP (Bluehost) but as usual they were useless. TSR tried to get me to change the setting to IMAP. I have read about how that setting makes things slower. And that shouldn't fix anything since, again, both accounts have identical settings except for the email address. Whatever logs or whatever the TSR looked at, did not reveal any issue to him.