Regarding Lua, I can keep using it (I am nothing if not adaptable) but if C# ends up having faster execution than Lua, then it is an actual game-changer beyond just a preference for scripting.
As you move toward 3D you will find the extra horsepower starts to make sense. 3D has always been far more computationally expensive, especially at the scripting level. More of everything is required: math, AI, queries, optimisation, etc etc
It’s very likely Lua will be the bottleneck.