[Phanx]

You're missing the point by a very large margin. The point is not that calling Function A can get you info faster than calling Function B under Circumstance X. The point is that calling a function at all is much slower than assigning an extra variable, and you should not call functions if you don't need to -- specifically, there is almost no reason to ever use select.

Using your example, you should not do this:

local textureIndex = select(3, GetMapLandmarkInfo(i))
if textureIndex == 128 then
   -- do something
end

Instead, you should do this:

local _, _, textureIndex = GetMapLandmarkInfo(i)
if textureIndex == 128 then
   -- do something
end

You can get the exact same information from the exact same function, without the overhead of a second function call that's completely unnecessary and does not affect the information obtained or the source of the information.