Mike Ash on ARM64
Friday Q&A 2013-09-27: ARM64 and You | mikeash.com
Adding it all together, it’s a pretty big win. My casual benchmarking indicates that basic object creation and destruction takes about 380ns on a 5S running in 32-bit mode, while it’s only about 200ns when running in 64-bit mode. If any instance of the class has ever had a weak reference and an associated object set, the 32-bit time rises to about 480ns, while the 64-bit time remains around 200ns for any instances that were not themselves the target.
In short, the improvements to Apple’s runtime make it so that object allocation in 64-bit mode costs only 40-50% of what it does in 32-bit mode. If your app creates and destroys a lot of objects, that’s a big deal.
Mike Ash on ARM64 | John Gruber