KVO 100x slowdown in El Capitan

kvoperf.m

#import <Foundation/Foundation.h>

@interface Subject: NSObject

@property double a;
@property long b;
@property NSObject* c;
@property NSObject* d;
@property NSObject* e;
@property NSObject* f;
@property NSObject* g;
@property NSObject* h;
@property NSObject* i;
@property double j;
@property double k;
@property double l;
@property double m;
@property double n;
@property long o;

@end

@implementation Subject
@end

@interface Observer : NSObject
@end

@implementation Observer

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context {
}

@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSArray *keys = @[@"a", @"b", @"c", @"d", @"e", @"f", @"g", @"h", @"i", @"j", @"k", @"l", @"m", @"n", @"o"];
        Observer *observer = [Observer new];

        NSMutableArray *positions = [NSMutableArray array];
        CFAbsoluteTime start = CFAbsoluteTimeGetCurrent();
        static const int Max = 1000;
        for (int i = 0; i < Max; ++i) {
            Subject *position = [Subject new];
            for (NSString *key in keys) {
                [position addObserver:observer forKeyPath:key options:(NSKeyValueObservingOptionOld | NSKeyValueObservingOptionNew | NSKeyValueObservingOptionInitial) context:0];
            }
            [positions addObject:position];
        }
        CFAbsoluteTime end = CFAbsoluteTimeGetCurrent();
        printf("%.6f\n", (end - start));
        exit(0);
    }
    return 0;
}