How to Resolve Thunderbird High CPU or Memory Usage Issues.
If Thunderbird is causing high CPU or memory usage, continue below to resolve the issue. Thunderbird is a popular email client, but sometimes it behaves abnormally with excessive CPU or memory usage that can cause your system to hang.
The problem of high CPU or memory load caused by Thunderbird can be due to several reasons, but the most common ones are the following:
- A problematic Thunderbird setting or Add-on.
- The Windows Search feature in Thunderbird messages may cause Thunderbird to hang.
- The Global Search and Indexer feature may cause high CPU usage on Thunderbird.
- Thunderbird's Global Database is corrupted.
- Outdated Thunderbird version.
How to FIX: Thunderbird Uses a Lot of Memory or CPU Resources in Windows 10.
Method 1. Disable Thunderbird's Add-ons.
Thunderbird can make your CPU run at 100% or consume many Megabytes (MB) of your memory because of an installed extension (Addon). To troubleshoot problems with Thunderbird's Add-ons, proceed as follows.
1. Press and hold down the SHIFT key on your keyboard and open Thunderbird.
2. At the next window click Continue in Safe Mode.
3. If Thunderbird is not freezing in Safe Mode, then an installed add-on may cause the problem. In this case:
- Close Thunderbird.
- Press the SHIFT key and launch Thunderbird again.
- At the next window, check the option Disable all add-ons and click Make Changes and Restart.
4. If the problem persists, continue to the next method.
Method 2. Disable Windows Search to search messages.
1. From Thunderbird's menu, select Tools > Options.
2. In General settings, under the System Integration section uncheck the option Allow Windows Search to search messages. This setting prevents Windows Search from indexing Thunderbird messages, which can reduce CPU usage as the indexing process is resource-intensive.
3. Restart Thunderbird.
Method 3. Disable Global Search & Indexer.
1. From Thunderbird's menu, select Tools > Options.
2. In General settings, scroll the page down and under Indexing uncheck the option Enable Global Search and indexer, which stops Thunderbird from indexing all messages globally, a process that can consume significant CPU resources.
3. Restart Thunderbird.
Method 4. Rebuild Thunderbird's Global Database.
In some cases, Thunderbird can use a lot of CPU or memory resources because the Global Indexing Database becomes corrupted. So, the next method to solve the "Thunderbird high CPU usage" issue is to force Thunderbird to rebuild the indexing database. This process involves deleting the current database file, prompting Thunderbird to create a new one, which can resolve corruption-related performance issues.
* IMPORTANT: Before continuing, it is recommended to backup the Thunderbird profile folder in case something goes wrong.
1. Close Thunderbird.
2. Navigate to the Thunderbird default profile folder on your disk: *
C:\Users\username\AppData\Roaming\Thunderbird\Profiles\ProfileName.default
* Where username is your Windows username and ProfileName is the Thunderbird default profile folder.
3. Find and delete or -better- move to another location (e.g., on your desktop), the following file: global-messages-db.sqlite
3. Open Thunderbird and let it re-index your messages. *
* Note: The re-indexing process will start automatically and will take some time to complete, depending on the number of messages. During this time, you can use Thunderbird, but you may experience performance issues, and the search may not return all results until the indexing is complete. The progress of indexing can be monitored via the Tools > Activity Manager menu.
Method 5. Increase the time before Thunderbird goes Inactive.
Thunderbird goes to sleep after 5 minutes of inactivity (300000 milliseconds) and loads all messages when it becomes active again. This behavior sometimes results in high CPU usage from Thunderbird, as mentioned in this bug report.
So, another method to fix the problem of Thunderbird's high CPU usage is to increase the time before Thunderbird goes idle. (For more info about this solution see here.)
* Important: I suggest before applying the steps below, to check if the issue persists after installing the latest version of Thunderbird, because many users reported that the problem is gone after installing the recent TB update. (To update Thunderbird: Go to Help menu, select About & then click the Update button if an updated version is available).
To increase the time before Thunderbird goes to Idle.
1. From Thunderbird's menu, select Tools > Options.
2. In General settings, scroll the page down and at the end open the Config Editor.
3. In the search area type: mail.db.idle_limit and then click the Edit button next to the result below.
4. Add two (2) more zeros (0) at the end of "300000" to become 30000000 and hit Enter.
5. Restart Thunderbird to apply the change and check if the high CPU usage remains when Thunderbird is open. *
* Note: If the issue persists, follow again the steps 1-3 above, but this time click the Reset button 
to restore the mail.db.idle_limit to its default value.
Method 6. Scan for viruses & Check your Antivirus program.
If after applying the above methods you still face high CPU or Memory load when running Thunderbird, I suggest using this Malware Scan and Removal Guide to check and remove viruses and/or malware that may be causing the mentioned problem, or try temporarily disabling your antivirus program to see if this is causing the problem.
- Related article: FIX: Thunderbird Not Responding or Freezing.
Method 7. Update Graphics Drivers
Outdated or incompatible graphics drivers can sometimes cause Thunderbird to consume excessive CPU resources. Ensure your graphics drivers are up-to-date by visiting your graphics card manufacturer's website, such as NVIDIA or AMD, and downloading the latest drivers for your specific hardware. Updated drivers can improve system performance and resolve compatibility issues that may affect Thunderbird.
Method 8. Adjust Thunderbird's Hardware Acceleration
Hardware acceleration can sometimes lead to high CPU usage if the system's hardware is not fully compatible. To adjust this setting, navigate to Tools > Options > General and look for the hardware acceleration option. Disabling this feature can reduce CPU load by allowing the software to handle rendering tasks instead of the GPU.
Summary
In summary, resolving Thunderbird's high CPU or memory usage issues involves a multi-step approach. Start by disabling add-ons and unnecessary features such as Windows Search and Global Indexer. Rebuild the Global Database if corruption is suspected. Adjust idle settings to prevent unnecessary CPU load and ensure your system is free from malware. Additionally, updating graphics drivers and adjusting hardware acceleration settings can further optimize performance. By systematically applying these solutions, you can significantly enhance Thunderbird's efficiency and reduce its impact on system resources.
Frequently Asked Questions
Why is Thunderbird using a lot of CPU or memory on my system?
High CPU or memory usage in Thunderbird can be caused by problematic settings or add-ons, Windows Search features, the Global Search and Indexer feature, corrupted global database, or having an outdated version of Thunderbird.
How can I determine if a Thunderbird add-on is causing high CPU usage?
To check if an add-on is the problem, start Thunderbird in Safe Mode by holding the SHIFT key while opening the software. If the issue does not persist in Safe Mode, an add-on may be causing the problem. Disable all add-ons and restart Thunderbird to see if that resolves the issue.
How do I disable Windows Search in Thunderbird to reduce CPU usage?
To disable Windows Search, open Thunderbird and go to Tools > Options. Under the System Integration section in General settings, uncheck the 'Allow Windows Search to search messages' option, then restart Thunderbird.
What should I do if Thunderbird's Global Database is causing high CPU usage?
Rebuilding Thunderbird's Global Database might help. Close Thunderbird and navigate to the default profile folder. Delete or move 'global-messages-db.sqlite' from your disk. Open Thunderbird again and let it re-index your messages, which will take some time.
