How can I adjust the speed of an NSImageView animation?

Question

I'm using the NSImageView.animates property to play a GIF in SwiftUI as follows:

struct GIFView: NSViewRepresentable {
    var gifName: String

    func updateNSView(_ nsView: NSView, context: NSViewRepresentableContext<GIFView>) {    }

    func makeNSView(context: Context) -> NSView {
        return GIFPlayerView(gifName: gifName)
    }
}

class GIFPlayerView: NSView {
    private let imageView = NSImageView(frame: CGRectMake(0,0,200,200))
    
    convenience init(gifName: String) {
        self.init()
        let asset = NSDataAsset(name: gifName)!
        let gif = NSImage(data: asset.data)!
        imageView.animates = true
        imageView.image = gif
        self.addSubview(imageView)
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

This works, but the playback speed is slower than I would like. I tried converting the image data into an NSBitmapImageRep and changing the currentFrameDuration for each frame, but it doesn't seem to have any effect on the actual playback speed:

        let asset = NSDataAsset(name: gifName)!
        let bitmap = NSBitmapImageRep(data: asset.data)!
        let count = bitmap.value(forProperty: .frameCount) as! Int
        for i in 0..<count {
            bitmap.setProperty(.currentFrame, withValue: NSNumber(value: i))
            bitmap.setProperty(.currentFrameDuration, withValue: NSNumber(value: 0.01))
        }
        let gif = NSImage.init(size: bitmap.size)
        gif.addRepresentation(bitmap)