If your problem is gone with the operating system in safe mode, then the cause can be antivirus or some other software loading during the OS startup. First StepsĪ quick test of the impact of antivirus software (AV) is starting Windows in safe mode, or starting Mac in safe mode. In short, if TB performance is good when AV software has been disabled, doesn't make this fundamentally a bug in Thunderbird, although there are certainly areas of Thunderbird performance that can be improved.

AV vendors don't always play nice, and don't always adapt their software to new versions of other software on your computer, whether you know it or not they do make accommodations under the hood for how they interact with other software. Yes even if Thunderbird is the only software affected, even if your AV version did not change. Antivirus and Thunderbird have a complex relationship, and that relationship can be broken by updates or version changes of either software. But this is NO guarantee it is working correctly now. Warning: Your antivirus software probably worked great for months or years, across many previous versions of Thunderbird. I even tried disabling my antivirus software. Thunderbird is the only program that is affected. My Antivirus software has been working great.

Initial mailbox indexing for global search.

Downloading or attempting to get new messages (receiving mail).

Replying to a message / Sending a message.

Does excluding Thunderbird profile directory from scans put my system at risk?.

Diagnosing Memory Usage Problems & Performance.

(create a wiki account, and click 'edit') If you have a problem that is not listed here, please add it to the list so other users can benifit. Much of the information below is from users like you.

Antivirus software can also cause odd behavior (bad, incorrect or unusual), and crashes (random or consistent, infrequent or frequent). This article is not just about performance issues. 9.2 Solution: Disable Windows System Proxies.9.1 Problem:Windows System Proxy blocking HTML images anecdote.9 Bogus Windows System Proxies Left by Malware.7.4.6 AVAST blocks images in HTML email.7.4.5 Avast Blocks Sending and Receiving.7.4.4 Avast 2015 causes invalid mail server certificate warnings sending/receiving mail.7.4.3 Hangs with 'Allow anti-virus clients to quarantine individual incoming messages'.

7.4.2 Slowness and errors with nsemail.HTML.7 Configuration Notes and Solutions for specific Anti Virus products.5 Problem Antivirus and Anti-Malware Packages.4 Testing Suggests My Problem is Caused by Antivirus Software.2 My Problem Cannot be Caused by Antivirus.

Avast check for viruses on my computer