Change McAfee to scan programs and documents and see the speed improve.

Now it is not uncommon for Thunderbird to use twice as much space as Gmail (Thunderbird historically kept a copy on mail in the ALLMAIL folder and also the other folders they lived in.

However 10 times is not right. Have a look for one or two exceptionally sized files and post their names.

also check that the setting in Tools menu (Alt+T) > account settings > server setting is set to expunge the inbox on exit.

Additionally.... File menu (alt_F) > compact folders.

Thanks for your valuable help, Matt.

I already compact my TB folders on a weekly basis, no improvement from that.

Actually, inside imap.googlemail.com, there is a huge [Gmail].sbd folder (20,2 Go). Inside this folder there are 31 nstmp-xx files. They range from 0 Ko to 2 404 437 Ko ! What do these files mean ? Can I delete them without harm ?

Further precision : the Inbox file isn't inside [Gmail].sbd - don't know if it's OK - but inside imap.googlemail.com and amounts to 200 Mo. I also have 5 nstmp files on imap.googlemail.com but they don't exceed 150 Mo.

I haven't selected to expunge the inbox on exit : will it delete all the mails I have read before I can download them on both my computers ? 2 or 3 times a year I clean everything on Gmail. My gmail account weighs "only" 2 Go while imap.googlemail.com weighs 20 Go on my disk !

Thanks for all new tricks to solve my problem.

in Thunderbird View menu (ALT+V) > folders ALL

look for those nstmp folders in basically the same location you saw the files on disk.

If you find them in Thunderbird delete them there. Otherwise if there is no appearance in Thunderbird delete them in the file system. (On this occasion it is perhaps wise to make a backup of the whole 20Gb just in case the worst happens. If Thunderbird is Ok at the end you can delete than to.

When you compact, Thunderbird builds a new storage file for the mail. (NSTMP stands for Netscape Systems Temporary File) The NSTMP file is opened and the mail that is to be kept is copied to the new file. At the completion of the process, the original file is actually deleted and the NSTMP file is renamed to replace it. If a compact is in progress when you exit Thunderbird (usually a system shutdown) the process aborts and the temp file is left behind (deliberately in case some mail is missing on restart)

So deleting these files is not really an issue. It is just that they almost always appear in Thunderbird under the folders there and if so that is the appropriate place to remove them.

Thanks a lot, Matt.

It works real fine now. I backed the NSTMP files and deleted them on the system disk and it's OK now. I lost 20Go on the system disk and TB is fast now.

Thanks !