Pop or IMAP?

If IMAP is this a gmail account?

• If yes, do you see an 'All Mail' folder?
• If yes, Unsubscribe from the 'AllMail' folder as this will double the amount of space used.
• see info: http://kb.mozillazine.org/Using_Gmail_with_Thunderbird_and_Mozilla_Suite

If IMAP, do you synchronize your folders? If yes, do you choose to download ALL of the folder or do you choose to synchronize the most recent xx days or emails?

• see info: https://support.mozilla.org/en-US/kb/imap-synchronization#w_configuring-synchronization-and-disk-space-usage

Larger folders take up more space and memory, so do you archive emails that are older than eg: 60 days to reduce the size of the file? Otherwise you are constantly synchronizing huge files of emails that you are most likely not needing to see. You do not have to subscribe to see the Archived emails unless you need to.

Do you compact folders on a regular basis (I will do this daily as I receive and delete several messages) ? Compacting will remove tracess of 'marked as deleted' emails, otherwise the folder can be larger than it appears.

• compacting info: http://kb.mozillazine.org/Compacting_folders

What anti-virus software are you using? Are you scanning all incoming and outgoing mail?

Do you empty and compact/expunge your 'Deleted' and 'Junk' folders on a regular basis?

General info on things that can effect performance:

• http://kb.mozillazine.org/Performance_%28Thunderbird%29

Hi, Thanks for your comprehensive reply. Unfortunately at this moment I cannot even open my Thunderbird!

I do read, move incoming mail I want to keep + my replies to specific sub foldesr, I delete all unwanted messages and empty 'trash' on a daily) basis.

I don't have more than 200 incoming messages in my 'In' folder at any one time... and try my best to reduce to below 75 remaining in 'In' by the end of the day. Almost all these will have been opened and read.

I use MacAfee, which I know has been a problem in the past but I have had about 6 months uninterrupted good use, then the past 2 weeks has been difficult, and today totally impossible.

I hope I can open Thunderbird again shortly as this is hindering work..... I will then examine all the otehr items you have mentioned. Thanks, Carol

P.S. My account is GreenNet http://www.gn.apc.org/ .. and not gmail.

Close Thunderbird.

Then suggest you stop MacaFee from scanning the emails.

see this info:

• https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues#McAfee

Then open Thunderbird.