1.5.3 raised the speed ladder to 10x and said a run plays out identically at 1x and at 10x. Two things made that not quite true. This is a hotfix for both.
The game leans on the brakes for a beat when something big lands: a kill, an explosion, a tower surge. Enemies dilate for a fraction of a second while your towers keep firing, and it is what makes a hit land.
Those beats were measured in real seconds, but the things that trigger them run on game time. At 10x that meant roughly ten times as many beats arriving every real second, each still holding for the same real duration, and they piled up on top of each other. Enemies spent up to a quarter of the time crawling at a fifth speed and then snapping back, over and over, which read as the whole field lurching rather than as any single hit landing.
Every beat is now measured in game time. One hit still reads exactly as it did at 1x, and the top of the speed ladder is smooth again.
Tower surges re-armed on a real-time cooldown. The intent was to keep the surge cadence looking the same at any speed, but a surge is not only a light show: it carries a damage payload, and tower surges are what charge the Global Surge bar that fires your operator's active.
So the cooldown was quietly rationing all three. At 10x a board was getting about a third of the surges it should have per unit of game time, and about a quarter of the operator casts. Fast-forwarding through a wave was costing you real damage, and the deeper the run the more it cost, because those are exactly the waves you fast-forward.
Surge cooldown now runs on game time. Surges, Global Surge charge and operator casts all arrive at the same rate per wave whichever speed you are watching at.
Both fixes move in your favour: high speed gets back what it was losing, and nothing was made harder. Waves play the same at 1x as they always did.