Comment by Metasyntactic

Hi there, one of the C# lang designers here. I discuss this a bit in https://news.ycombinator.com/item?id=48255658.

Contrary to what a lot of people guess, boxing is actually a really good strategy most of the time. And, is indeed what many people are doing here anyways. The design supports a pattern that allows for non-boxing, and I expect that we will both supply an implementation for that with reasonable defaults, and that source generators will be a great way to augment this to get highly specialized impl strategies for non-boxing depending on the varying domain needs any specialized customer may have.