Hook this up to a coupla text boxes and see NSAnimation only ever do 60fps, picture of sample interface at https://twitter.com/natevw/status/709516893917319168

AppDelegate.m

@interface MyAnimation : NSAnimation {}
@property NSUInteger frameCount;
@end

@implementation MyAnimation

- (void)startAnimation {
  _frameCount = 0;
  [super startAnimation];
}

- (void)setCurrentProgress:(NSAnimationProgress)progress {
    [super setCurrentProgress:progress];
    NSLog(@"Progress: %f", progress);
    _frameCount += 1;
}

@end


@interface AppDelegate () <NSAnimationDelegate>
@property (weak) IBOutlet NSWindow *window;
@property (weak) IBOutlet NSTextField *display;
@property MyAnimation *animation;
@end

@implementation AppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
  self.animation = [[MyAnimation alloc] init];
  self.animation.duration = 1;
  self.animation.animationBlockingMode = NSAnimationNonblockingThreaded;
  self.animation.delegate = self;
}

- (IBAction)updateFrameRate:(id)sender {
  NSTextField* input = sender;
  NSLog(@"New frame rate: %li", input.integerValue);
  
  [self.animation stopAnimation];
  self.animation.currentProgress = 0;
  self.animation.frameRate = input.integerValue;
  [self.animation startAnimation];
  
  self.display.stringValue = @"-";
}


- (void)animationDidEnd:(NSAnimation *)animation {
  self.display.integerValue = (NSInteger)self.animation.frameCount;
}

@end