i think the problem is that with x4 speed they cannot test properly the way the boosters and construction/shipyard robots work with the balance of the game.... but it's true, x4 speed is much more fun
I prefer the speed universes also. 4x at the least, but I prefer even faster. 7x is my speed of choice.
But I understand the need to test the accelerated boosters at slower speeds so actual boost factors can be verified. Once speed boosters and other accelerators have been checked, perhaps a speed increase back to 4x can be considered.