Summary
Knowing how to make a game sometimes isn't enough; you also need to know how to make a game the right way. This is to make sure that your game runs fast enough even on slower mobile phones. There are a lot of things you can do to make sure that the performance runs well enough, starting from testing it on mobile phones from the beginning to make sure that you know how your game runs on mobile devices. You can increase performance by not creating a lot of objects on the screen because this slows down the game. You should also remember that physics objects are CPU-intensive, so try not to use too many of them.
In using your assets, you need to remember the best file format to use; use a 32-bit PNG file for images and a 16-bit WAV file for sounds. Construct 2 converts the audio to appropriate file formats to use for all range of browsers. Also, when using images for your games, it's better to use a lot of small images rather than a single big one.
You now know how to make games...