[nponeccop]

My point is that 2x slowdown is critical for many systems - embedded, gamedev, HPC, systems software. Controlled measurement of slow-down and heap slack caused by GC is beyond capabilities of most embedded devs. Academia provided us with some experimental results saying that in half-empty heaps GC is lightning fast, but there's no (recent) data for 90% full heaps and for very large heaps.