About ref used for performance reasons with struct

[Steven Schveighoffer]

On Mon, 11 Feb 2013 10:08:52 -0500, deadalnix <deadalnix at gmail.com> wrote:

> A good rule of thumb to know when to pass by ref for perf is :
>   - The struct is big, or contains mixed entities (floats and ints).  
> 2*size_t seems like a good heuristic from my experience.

Array slices are 2*sizeof(size_t).  I would expect them to be always  
copied and not ref'd.

-Steve