do you have an anti virus on your laptop? They tend to cause similar issues on Windows.

I do not use any of antivirus on MacOS. I have almost pure system...

Do you have Mac Spotlight turned on in Preferences/Advanced/General/System Integration? In the same place, does it help if global search and indexing is disabled?

These are two factors listed here:

https://wiki.mozilla.org/Thunderbird:Testing:Memory_Usage_Problems

Yes, I have enabled system integration. I switched this option manually on but as has been disabled, also taken battery really fast. What you mean global search? About indexing? See the screenshot.

(I use Polish language)

'Global search' is indeksowanie wiadomosci i wyszukiwanie. You should uncheck the box for that as well as for Spotlight, and see if it improves performance. Since you say the Spotlight integration was already disabled, the problem may be with global search. Either the database is corrupted, or you have a very large number of messages to index, and this is causing a performance lag. This article explains how to repair a corrupted database.

Already switched off both of those option. Does the hardware acceleration should be also "off"? (I have "on").

Stupid... normally the battery during an hour fall around 10% but when I open the Thunderbird (no matter if is minimized or on desk) it takes around 20%...

There's no universal rule for hardware acceleration. If it was on, turn it off and see if it makes a positive difference or none at all.

No of the settings seems to work properly... :(

Have you rebuilt the Global Database?

• Exit Thunderbird
• Access profile name folder
• rename 'global-messages-db.sqlite' to say 'global-messages-db.sqlite.old'
• Start Thunderbird.

Any change?

Did you test to see if offline mode effects the cpu?

• Start Thunderbird in 'Offline' mode - do you still get same issue whilst in offline mode?

• Exit Thunderbird
• Access profile name folder
• what size is the 'panacea.dat' file ?
• delete 'panacea.dat' file
• Start Thunderbird.

Do you have any newsgroups ? If yes, are there many messages that are not read? Select the messages as read.

Ok, so I tried to fint the file you said about, but there is no file named as you said. Also, the MacOS doesn't have any of "profile name folder" - have some kind of "program libraries" and I can not find this file there.

Seems that CPU is also corrupted via offline mode. BUT! I see now even if the program has online of offline mode but is minimized the CPU seems to be not corrupted. (all of above function I have now disabled).

Hi individualacc, I'm also on macOS, but I'm not experiencing any memory issues (indexing and hardware acceleration enabled), so I should be able to help you.

First, let's make sure that you are using the latest version of Thunderbird. Please go to Thunderbird > About Thunderbird to check if there are updates available and install any updates. The latest version (at the time of this post) is 68.1.1.

If you're up to date, and the problem still persists, go to Help > Restart with Add-ons Disabled. This is a troubleshooting tool that will disable some things to help you narrow down the cause of a problem.

• If the problem does not occur, then you can disable your extensions one-by-one until you find out which one is causing the problem.
• If the problem still occurs, we'll need some more info about your Thunderbird setup.
  1. Go to Help > Troubleshooting Information then click Copy text to Clipboard.
  2. Go to https://pastebin.com and go to Edit > Paste to paste the info from your Troubleshooting Information page, and click Create New Paste.
  3. In Safari, control-click on the address bar, and select Copy.
  4. Open a reply to this post, and go to Edit > Paste to paste the link to your troubleshooting information.

I have version 86.1.1 already.

I just tried to use the Thunderbird in safe mode and it seems to solve the problem. But, I have no extra add-ons installed. Just installed the program and login into the mail... ;(

If you have no add-ons except Lightning, but TB works in safe mode, the next thing to try is start in safe mode, check "Reset toolbars and controls' and click 'Make changes and restart'.

http://kb.mozillazine.org/Safe_mode#Safe_Mode_options

I'm going to check and see for a few days how it will going to work. Thank you all for help. I do not close the ticket yet ;)

Solved. no issues anymore. Btw, I got a new MacOS, Catalina - also no issues.