Silent Spell costs 1 action, but allows you to waive the spell's verbal component. Does waiving the verbal component reduce the spell's action cost by 1, thus producing no net change in the number of actions to cast the spell?
The total number of actions does not change
Silent Spell states (emphasis mine):
If the next action you use is Casting a Spell that has a verbal component and at least one other component, you can remove the verbal component.
The verbal component is one of the actions of most two- or three-action spells. If the verbal component is removed, only the material and/or somatic components are necessary to cast the spell. Since this feat adds one action and removes one action, the total number of actions does not change.