This is a WIP (playable) a live server link to the game is available at the bottom of this post (be patient the game takes a long time to load after you click/ touch the "Click to play" button). It is a skeleton for a 2D underwater game I am a 3D character designer & animator at the base and decided I would like to create a game. I started out using HTML5 Canvas & Javascript then I discovered Godot, Amazing!
Game optimization is one of my first questions here, Is this due to my original image sprite size of 600px by 600px and then scaled accordingly inside the engine? Some of the animation cycles are 60 frames long and the game takes over 2 mins to load (this makes people think that the start button has not triggered and they press it over & over this is a problem).
Player damage is another of my questions I have a Timer and TextureProress bar indicating air. The player (Scuba diver) has to surface to reset the timer it works but I would like to know how to make this a random value so that the time is not always the same each time. The HUD where the timer is is on a Canvas layer and instanced into the main scene. At the bottom of the game when you arrive at the reef there are crabs I would like this to work as follows as the Player collides with the air TextureProgress gauge speeds up x2. In-scene collisions work fine like the enemy (Crab) changes direction based on the Player's position and attack animation works My problem seems to be when the event is called from another instanced scene.
Right now I just have collectibles coins/ treasure connected up to a scoring system as the game logic this will all change in future releases as I want this to be an adventure, for example, find the key first then it will open the treasure chest then you will get a coin, etc.
Thank you in advance for any help you may be able to give me to help me advance in my game project and improve my Godot .GD coding skills. Warning the links do not work on a 4G/ 5G network you must be connected to your wifi or home LAN (something to do with IPv6 Server configuration)

Link to the blog article about the game: https://thehiveprojet.fr/blog-detail/under-water-game-characters
Direct link to the game: https://thehiveprojet.fr/presentation-projects/scuba/scuba-dive.html