What do you want to achieve? Keep it simple and clear!
Currently I’m using a Localscipt in ReplicatedFirst to hide all CoreGUIs upon joining. Is this method efficient or is there an easier and faster way at doing so?
local StarterGui = game:GetService("StarterGui")
StarterGui:SetCoreGuiEnabled(Enum.CoreGuiType.All, false)
I’d like to have it instantaneous so that the client would never see any CoreGUIs when in the game.
There literally isn’t. Roblox only provides so much methods, and these are coreGUIs you mean. The best you can do is use SetCoreGuiEnabled(), and you definitely can’t hide the menu button.