SKTransition Problems and scene loading - ios

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.