Unfortunately, reference counting has abysmal performance [6, 8, 16]. Conservative GC performs better, but it cannot support copying which is critical to high performance GC [7, 8]. If the language implementors decide later to get serious about performance, they have a conundrum since retrofitting support for high performance collectors is typically very hard, if not impossible. If the compiler implementation does not build on a foundation that uses the discipline of exact GC, fixing it later is a nightmare.