1. Turn off the message pane

When the message pane is on, any e-mail clicked will download every time you click on it. When turned off it makes for going thru mail much faster (especially for those of us who deal with large file attachments).

Turn off message pane: Press F8.

Turn back on message pane: Press F8 again.

Wax on.. wax off..

Tip: Have the "Size" column enabled in Thunderbird so you can easily distinguish small e-mails from large ones.

The Size column is available for view from the far right side. See image below for example.

2. Use [Gmail] as your root IMAP folder.

Where this is:

Tools / Account Settings / Server Settings (left) / Advanced (button right)

Looks like this:

And yes you literally type in [Gmail] – brackets and all.

This will make your Thunderbird inbox look identical to your Gmail inbox – and will make your mail run faster because it the "tag" folders won’t be polled for e-mails (which are literally copies of mails in "All Mail" anyway).

3. Do NOT have Thunderbird auto-copy sent mail to the Sent Mail folder.

Where this is:

Tools / Account Settings / Copies & Folders / Uncheck "Place a copy in:"

When you send a mail from Thunderbird using the Gmail servers, it automatically puts a copy in the Sent Mail folder in your Gmail account. What this means is that you don’t need to have Thunderbird do it again, so it’s safe to disable it.

If you send large attachments routinely, this is a humongous time saver.