Sounds like unrealistic expectations to me. My classics have all been understood to be just that - never to be compared with the newer, more sophisticated vehicles that I use for specific purposes or daily driving. If one climbs into a '66 automobile and thinks it should perform like a 2021 example, one just doesn't "get" what the idea really is, in my opinion.
Likewise, I'd never board a 1950 Piper Cub and expect that it was going to take me somewhere with the speed and comfort of a Boeing 777. My advice: stop comparing and just enjoy the blast from the past! 😊