Okay, I have covered the common and technical things you should know when you want to squeeze the best performance out of your games. However, there's another thing you must know when developing your games: memory. Mobile devices have limited memory resources, so always keep memory usage in mind when developing on mobile platforms.
Maybe, you still remember that I said not to use too many sprites in your project, or if you need to use an image repeatedly, then it's better to use a Tiled background object instead, because Construct 2 counts it as one object. Another thing you must keep in mind is you shouldn't use image files that are extremely big or detailed in your game. If you're a designer and want to use an HD image for your level, just know that it won't work, especially on a mobile.
The reason is a bit technical, but let me try to explain. Images are made up of pixels, so an image of 1920 x 1080 pixels will consist of 2073600 pixels...