Sadly, this is a response to an issue in the system that means that sometimes resizing windows performs an animation. Changing a window position moves and resizes the window in two steps (there is no single API for move&resize). And if the resize happens while the animation is happing, then the system screws up both. To work around this and ensure reliability, Keyboard Maestro includes a delay between the actions.
So you can have fast and unreliable, or slow and reliable, but not fast and reliable.
You can turn this off with the Terminal command:
defaults write com.stairways.keyboardmaestro.engine WindowSetFrameAnimationTime -float 0.0
But you may find that some windows in some applications (including Safari and Mail) may start to fail to correctly perform move&resize actions.