hooksecurefunc() with local versions of functions?

[LudiusMaximus]

I understood that it is considered a good habbit to declare local versions of global functions to make your code use less CPU cycles.
(See e.g. https://www.wowinterface.com/forums/...ad.php?t=57151)

So I am particularly doing

local SetCVar = _G.SetCVar

because my program uses SetCVar() a lot.

But how can I now hook a function to SetCVar()?
For _G.SetCVar I would have used:

hooksecurefunc("SetCVar", MyPostSetCVar)

But this does apparently not have the desired effect, because it only hooks to _G.SetCVar
whereas my code uses the local SetCVar.

Do I need hooksecurefunc() at all to hook to my local SetCVar?
Or what would the first argument of hooksecurefunc() have to be for a local function?

Thanks!