Support for disabling ARC

[lukasa (Cory Benfield)]

@michaeleisel

Internally, however, memory management is done manually.

How are you manually managing the memory of Swift objects?

@michaeleisel

Did you know that adding trivial helper functions can cause extra retain/releases? This sort of thing causes a significant slowdown.

I do. We work with the Swift team to help provide these as test cases to improve Swift performance.