Thunderbird 115.4.0
After couple of years of not using Thunderbird (I switched completely to web portals) I tried it when they released Supernova and all I can say is that it's... slow. Really, I often have UI freezes, data doesn't appear immediately, downloading mails take a lot of time, calendar also is not that snappy. I somehow expected to have everything super fast as it's a local app (after all the data is downloaded), but it clearly doesn't handle large amount of mails efficiently.