How to make remote function calls faster within a server script?

In my game, there is a move where the player fires a series of beams from their arms (it has to be a server move instead of a client thing), but in order to get their mouse position, the client has a single remote function (which is shared with all the other players) where the server invokes to that client for their current mouse position. It does this 10 times with a wait of 0.4 seconds in between.

However i noticed that when NPCs are spawning in, this process isn't called every 0.4 seconds but rather 0.8 second which is significantly slower. Could this be because the remote function is shared by all players?

If that is the case, would it be better to give each player an individual remote function which the server script can call?