To diagnose problems with Thunderbird, try the following:

• Restart the operating system in safe mode with Networking. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: Windows 8, Windows 7, Windows Vista, Windows XP, OSX

If safe mode for the operating system fixes the issue, there's other software in your computer that's causing problems. Possibilities include but not limited to: AV scanning, virus/malware, background downloads such as program updates.

Messages load slowly, but I can't access them right away. A green progress indicator at bottom of screen makes me think something else is happening. When that bar is finished, messages can be accessed. Is the delay because Inbox messages are also posted to: All Mail, Important and Spam folders. Do I even need the All Mail and Important folders? Don't know how T'bird decides which messages are important.

Did things still go slowly when your computer was in safe mode?

Now to your assumptions, most of which are wrong.

The important folder. Controlled by a setting on Gmail and faithfully replicated by Thunderbird. (Circles, Immportant, family and an other circles you may have in G+. )

Gmail does not use the IMAP convention of folders, instead they use labels. This makes everything about Gmail "funny" or "Odd". That is just a fact of life.

All mail is actually where gmail stores ALL mail. in the gmail world, it is the inbox that is a label on some mail in All Mail. Again faithful replicated from Google

Right click the account in the folder pane and select subscribe and simply unsubscribe from all the folders you do not wish to see.

MY Thunderbird is doing the same, it downloads the headers, but when I click on them no message, and at the bottom of screen is message "loading" but nothing is happening. The header will get stuck on one email and I can not click and get it to change. This is with version 45, which also corrupted my my email settings. I was able to reset my ISP account settings with the assistance of my ISP IT technician. Thunderbird version 45 still has problems that have not been resolved by the developers.

Where is the safe mode in Thunderbird? I do not see any "Safe Mode" in the pull down menus in Thunderbird-45.

Also many posters with this problem have obviously found the safe mode, and it did not help, so why keep on suggesting it when there is obviously another problem with TB-45.

How do I revert to the previous version that did not have all these problems?

jlh68 said

Where is the safe mode in Thunderbird? I do not see any "Safe Mode" in the pull down menus in Thunderbird-45. Also many posters with this problem have obviously found the safe mode, and it did not help, so why keep on suggesting it when there is obviously another problem with TB-45. How do I revert to the previous version that did not have all these problems?

If you were to click the links associated with the suggestions to use safe mode you would get instructions. Just for your information it helps many people and you are not in a position to comment. You have not tried it.

It is obvious from your posting that your technician has turned off the option to store messages locally. so when you click you have to wait for the message to download from the server. But I will not be posting further here. You have hijacked someone elses thread and they are probably not interested in your issues. They have or had problems of their own. Probably completely unrelated.