Michael TsaiVerified account

@gte My beef with people that don't grasp systems programming if they can't imagine how small optimizations in many APIs quickly add up!

@rosyna In my experience, low-level optimizations add up less than one might hope. @gte

@mpweiher @gte I disagree and point to cfprefsd, Objective-C 2.0, pretty much all Foundation/CoreFoundation classes, and Metal as evidence.

@rosyna I don't recall Objective-C 2.0 improving performance much, if at all. Can you refresh my memory? @gte

@mpweiher @gte Objective-C 2.0 allowed new optimizations to take place that weren't possible before due a backward compatibility requirement

@rosyna Example?

@mjtsai Things like non-pointer isa (http://www.sealiesoftware.com/blog/archive/2013/09/24/objc_explain_Non-pointer_isa.html …) wouldn't be possible if Class hadn't become opaque.

@mjtsai Fast enumeration. non-fragile instance vars also means unused ivars can be removed from a class definition.