Another tip: Make sure your code is as efficient as you can make it (if you've coded the application yourself.) Inefficient code can slow down a webpage tremendously.
If you are running a webstore on Magento ecommerce platform, I would highly recommend to you Defer JS for Magento 2 extension. It will increase the loading speed of your store pages by moving JavaScript elements to the bottom of the page and defer its parsing and loading. Check this Magento extension here: https://store.belvg.com/defer-js.html
