There was an important update for my Windows 10 few days ago. After updating, some programs required an update as well, including Thunderbird (it did not offer me to skip that step and demanded an update to be made). After this I started experiencing issues with my Thunderbird - starting with delays in opening a new window, search and even scrolling down, it simply freezes for some amount of time. As I manage several emails, connected to my work and I have to send up to 100 emails daily, it is very annoying with all those delays, while typing, checking email or simply opening a new window to compose the email. My work is taking as twice as long than it used to do before. Please, deal with that! As this is really frustrating and if you released an update - you have to make sure its working properly, as Thunderbird with the way it is working now seems to me like "broken" beta-version!