Replicating variable in single player

I know its a silly question but Im curios about this for optimization concerns. I am building a single player/multi player template for myself. When player chooses single player, my blueprints will ignore all multi commands etc.

Lets say I have a replicated or repnotify variable in single player. No session created. Would that variable add any additional process to CPU when compared with not replicated variable?

If you are not on a network, any variable marked as replicated acts as a normal variable would. There is no performance overhead or additional CPU process to worry about.

Realistically, there is no performance issue in a multiplayer environment when dealing with data.

The advice I give is to make your game run first, optimize later. I wouldn’t worry about things like this unless they actually become an issue.