OK I have a Galaga. When I first got it, it had a microswitch joystick and I installed some brand new microswitch buttons. I was happy with it.
Then later, I restored the control panel art, added the original joystick, and figured it now deserved leaf switch buttons since that's more authentic.
Well, to my surprise, shots do seem to "launch" quicker. With a microswitch, you press down amd the shot fires off once the plunger goes all the way down and finally "clicks" in the switch. With a leaf, the contact is made almost right away. The button only moves down a bit before the switch contacts. It's noticable. Just barely, but noticable.