I have owned a bunch of Contax Sonnars over the years. Pre war, post war, collapsible, f/2 and f/1.5. Actually now that I think about it, I must have owned every version. In my experience a properly adjusted Sonnar is still sharp wide open. Most Sonnars at this point have been messed with by internet hackers, or someone else along the way thinking they knew what they were doing, which I think is why people believe they are soft wide open. There is also the focus shift issue. The best of the post war Sonnars IMO was the Carl Zeiss. IIRC the Opton Sonnars had a tendency to separate. I stupidly sold off all of my Contax gear when I started using Leica. Dumb. I still have one IIIa CD body that works fine but is really beat up, and a pre war 1.5 Sonnar that is absolutely fantastic. I also have a Helios 103. If you want to shoot color I would recommend getting one. The lens is a real sleeper. Images from it have a look kind of in between a Sonnar and a Summicron. They are super cheap too, which is nice.
There is a way to wind them super fast. If you shoot the camera cradling it in your left hand you simply pinch the wind with your right thumb/forefinger. Twist your left wrist towards your body and twist you right wrist away from your body while spinning the wind with your fingers. You can wind it as fast as a Leica this way.