One of the top reasons of Magento speed issues with database read speed. To fasten the read speed of the database you should enable Flat Catalog. This will minify the number of database joins done when showing products and due to that the MySQL query complexity will be reduced.
Go to backend: STORES > Configuration > CATALOG > Catalog > Use Flat Catalog Category and put Yes.
Go to backend: STORES > Configuration > ADVANCED > Developer > CSS Settings and put the Merge CSS Files and Minify CSS Files as yes.
CDN, or Content Delivery Network, is an interconnected system of cache servers that use geographical proximity as criteria for delivering web content and actually helps your visitors to load pages faster as a result.
One of the Magento 2 features is out-of-the-box support of CDN and here’s where you may find set up for it: STORES > GENERAL > Configuration > Web > Base URLs (Secure) and input your HTTPS CDN URLs in here and let your customers enjoy fast loading speed.
In the System > Cache Management enable your cache.