SKTransition Problems and scene loading

Question

So I'm currently creating a game. I have a number of Scenes: Menu, settings, gameScene and GameOverScene.

Transition between ALMOST ALL scenes is without a problem, the code I'm using to transition is: (e.g. for menu to GameScene)

let secondScene = GameScene(size: self.size)
let transition = SKTransition.pushWithDirection(.Up, duration: 0.7)
secondScene.scaleMode = SKSceneScaleMode.AspectFill
self.scene!.view?.presentScene(secondScene, transition: transition)

However, my GameScene to GameOverScene is extremely glitchy. There is usually a lengthy pause.

The entire contents of GameOverScene is:

import Foundation
import SpriteKit

class GameOverScene: SKScene {


    override func didMoveToView(view: SKView) {
        let myLabel = SKLabelNode(fontNamed:"American Typrewriter")
        myLabel.text = "Game Over!";
        myLabel.fontSize = 45;
        myLabel.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame));

        self.addChild(myLabel)
   }
}

Therefore I believe it's unlikely that this is the cause of the delay in transition.

The code I'm using to invoke a 'game over' is:

override func update(currentTime: CFTimeInterval) {

if sprite.position.y < 100 {gameOver()}
}

func gameOver() {

    // Loads GameOver Scene //
    let secondScene = GameOverScene(size: self.size)


    // Creates vibration //
    AudioServicesPlayAlertSound(SystemSoundID(kSystemSoundID_Vibrate))


        func boatSink() {
        sprite.physicsBody = nil
        sprite.physicsBody?.affectedByGravity = false
        sprite.physicsBody?.dynamic = false

        let spritefly = SKAction.moveTo(CGPointMake(400,20), duration:2.0)
        car.runAction(spritefly) }



    let transition = SKTransition.pushWithDirection(.Up, duration: 3.0) 
    let nextScene = GameOverScene(size: scene!.size)
    nextScene.scaleMode = .AspectFill

    scene?.view?.presentScene(nextScene, transition: transition)        
}

I've experimented with the use of Delays, such as using:

let skView = self.view! as SKView
            let scene = GameOverScene(size: self.scene!.size)
            scene.size = skView.bounds.size
            scene.scaleMode = .AspectFill

  let time = dispatch_time(dispatch_time_t(DISPATCH_TIME_NOW), 1 * Int64(NSEC_PER_SEC))
        dispatch_after(time, dispatch_get_main_queue()) {



            let sceneTransition = SKTransition.doorsCloseHorizontalWithDuration(2.0)
            sceneTransition.pausesOutgoingScene = true;
            skView.presentScene(scene, transition: sceneTransition)}

To give time to load but this does not work.

I've also tried using 'pausesOutgoingScene' and pausesIncomingScene' to no avail.

I finally tried slowing the current scene to 0.0 using:

func pauseGameScene() {
        self.physicsWorld.speed = 0.0
        self.speed = 0.0
    }

though this just stopped the code from progressing any further.

My questions are: 1. Is there anything really obvious I'm not thinking about with my transitions? 2. Is there a way to load all Scenes in advance, I'm sure that this probably will only provide minor improvement but it is definitely an area I've not yet looked at.