I have tried kmail, Geary, mailspring before I landed on betterbird. I’m not sure what you mean with slow, but it works without issues on my pc. It does a lot of stuff, but it’s a fork of Thunderbird, which you want to exclude based on the initial thread. There are not a lot of linux clients even worth trying. Good luck finding your jam.

They are the most well known private equity firm, but when I learned they are in the 40th place of how many assets they own and manage I was flabbergasted… Worth giving in some more time to understand what happened to the financial world in the past 25-30 years. https://www.visualcapitalist.com/worlds-50-largest-private-equity-firms/ . Personally I can’t wrap my head around how much money this ultra rich club has.