Thinking about the no atmosphere caveat here made me think of Venus, which is the opposite of no atmosphere for solid/rocky bodies in our solar system.
Earth's low orbital velocity is about 7.8 km/s. It's common to tack on another 1 to 1.5 km/s for the gravity drag and to ignore atmospheric drag in comparison. It's true that modern vehicles often reduce thrust slightly near max-Q but it's not a huge effect.
But launching from the surface of venus with its 100 times higher atmospheric density and similar scale height poses a substantial penalty.
You could not accelerate at the same rate as Earth launches; you'd hit a brick wall from atmospheric drag, so you have to climb more slowly, and minimize the sum of the losses due to drag and gravity.
Is it possible to estimate how much larger these losses are on Venus compared to the roughly 1 km/s delta-v loss from Earth?
Has anyone already calculated how much slower you'd have to go at max-Q, or the number of extra minutes it would take to reach low Venus orbit (compared to Earth launch)?