Pushrod diameter question

I've always wanted to know when the heavy wall push rod becomes a weight penalty.
When does the thick wall of a "higher performance" 5/16 pushrod become too heavy? And I should use a thin wall 3/8 diameter push rod. If that thin wall 3/8 push rod could actually be lighter than the heavy wall 5/16 push rod.
My assumption is that a heavy wall 5/16 could very likely be heavier than a lighter wall 3/8 . I believe that I will keep valve train components as light as reasonably possible ($$.¢¢) in any performance application.
I guess I should order up some singles and find it out.