User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0 Build ID: 20170504105526 Steps to reproduce: Thunderbird -> Calendar -> right click any remote calendar (like google calendar) -> properties -> Refresh Calendar The refresh calendar options available are: - Every 30 minutes - Every 60 minutes - Manual Actual results: Sync a calendar every 60 minutes is a too high frequency for most calendars. Thunderbird freeze/slowdown every time a sync takes place. A User with 20 remote calendars will have one syncing every 3 minutes, this means Thunderbird will freeze/slowdown every 3 minutes. Calendars like "holidays" hardly change, there is no need to sync every 60 minutes. And if there is a need the user can perform a manual sync. Expected results: More options should be available, like: - every 2 hours - every 3 hours - every 6 hours - every 12 hours - every day - every 2 days - every week - every 2 weeks - every month - Custom The way to do it is available here: https://superuser.com/questions/591086/increase-calendar-refresh-interval-beyond-defaults-in-thunderbird-lightning Hope this "bug" can be fixed soon.
Calendar version is Lightning 4.7.8