Would average windspeeds increase or decrease if day length increased substantially on Jupiter? Is windspeed in Jupiter's atmosphere primarily driven by solar energy differentials between night and day side or something else? Would proximity to the sun (2x increase in radiation energy received) have an equal impact on windspeed to a 2x day length change?
Jupiter receives 28 times less solar energy than us, and generates about twice as much radiation as it receives, so most of the convection is due to to the latent inner themperature of Jupiter.
If the day lengths were longer, it might forment the convection of the atmosphere, and therefore decrease the wind speed of the high atmosphere by reducing drag.
The winds are the fastest on Saturn because it has less internal heat and less solar radiation, while the surface of the planet is a liquid which exerts very little drag on the atmosphere, and the winds there are 1000 mph.