So you do not have an issue with Thunderbird itself. You may have other programs working in the background or updates occurring. Is Thunderbird using IMAP or pop mail accounts? Maybe, you have alot of emails in several folders and therefore using alot of memory to run. Try some reorganizing. '''If Pop mail accoun'''t, set up Archive Options and archive anything over one month old by month and keep folder structure; including the Sent folder. * see info: https://support.mozilla.org/en-US/kb/archived-messages Then only open the Archive folder if necessary. * Create folders and move emails out of the Inbox into those folders. * Delete emails you do not want. * When Inbox is empty, right click on Inbox folder and select 'compact'. Empty Deleted and Junk folders and then right on each folder and select 'compact'. '''If IMAP mail account''' you could select to only download the most recent emails instead of all emails. * see info : https://support.mozilla.org/en-US/kb/imap-synchronization?esab=a&s=synchronize&r=0&as=s#w_configuring-synchronization-and-disk-space-usage If you have a IMAP gmail account, do not subsribe to see the 'All Mail' folder. This is gmails archive of all of emails, so subscribing to this folder only doubles the amount of disc space used. see more info under 'All Mail at this link: * http://kb.mozillazine.org/Using_Gmail_with_Thunderbird_and_Mozilla_Suite By doing the above, you should have smaller folders and so use Thunderbird will use less memory. Then you would need to see if this helped. You may need to check to see if you have other background processes going on that are not connected to Thunderbird.

Thanks for the help! I rarely empty my trash and sent mail folders, and didn't notice how much it builds up. After deselecting all folders except for the inbox, I don't notice any slowdown at all! Thanks for the quick and helpful response. :)