Comment 98 for bug 215194

One IMAPS account and 2 CalDAV accounts with HTTPS URLs. All connecting to the same host through a slow VPN connection (It's harder to reproduce is the network is fast). CPU is Quad core so I get 25% cpu usage when the bug happens.

With TB2:
1) Send a 500k mail to yourself, quit TB main window while it's sending (so TB quits right after the mail is sent)
2) Start TB again, click on the new mail header, quickly go to calendar pane and do a "reload calendars", go back to mail headers and click on the new mail again.

With my setup I can reproduce it about 50% of the time in the first 5 seconds of starting it up (After that it usually never locks up).

The same test with TB3 does not seem to cause any issue.