why is PHPhotoLibrary performChanges creationRequestForAssetFromVideoAtFileURL so slow?

Question

I'm measuring times from tens of seconds to minutes depending on the size of the video. Shouldn't this change request be fast (local flash disk copy/meta data/checksums) as it adds a local video to the photolibrary/camera roll? This issue appears to occur when iCloud backups are turned on. I haven't been able to find much helpful information through web search or the apple dev docs.

Sample code:

    func exportAssetToPhotoLibrary(videoURL: NSURL, _ exportedAsset: (localIdentifier: String) -> Void) {
        var localIdentifier = ""
        var startTime = NSDate.timeIntervalSinceReferenceDate()
        PHPhotoLibrary.sharedPhotoLibrary().performChanges({
            let assetRequest = PHAssetChangeRequest.creationRequestForAssetFromVideoAtFileURL(videoURL)
            let assetPlaceholder = assetRequest.placeholderForCreatedAsset
            localIdentifier = assetPlaceholder.localIdentifier
        },
        completionHandler: { success, error in
                var elapsedTime: NSTimeInterval = NSDate.timeIntervalSinceReferenceDate() - startTime
                NSLog("exported cameo video to photo library \(elapsedTime)")
                exportedAsset(localIdentifier: localIdentifier)
        })
    }