Hello. Today I will make a tutorial on how to downgrade the size of the game. I usually use it for my game, and it works perfectly.

Before you do it, make sure your game is a copy.
I use the Construct 3 engine to export the Mummy Slot game.

Construct 3
The Mummy Slot

After that, I use the png compress service to reduce the size of all images.
I recommend some websites below.
https://compresspng.com/
https://tinypng.com/
https://www.iloveimg.com/

I choose tinypng to compress my game.

tinypng.com

After I got my images and replace them in the image folder. How surprising, the size game reduces 79 percent.

Small tutorial, hope it helps you to save resources and speed up when load HTML5 game.