couple points on this.

1) absolutely, we should add some IFDEFs for debug, but not because the function, but because of the extra memory for storing false color.

2) It's very important to understand how I wrote this function... namely, since it's a const function, and it returns a const& to a member. The compiler is smart enough to basically turn this into a direct memory access of the member variable. (except for the false/true feature, which yes, to point 1 we should IFDEF).

So... ultimately, being a function is not a performance concern.