How to optimize the website in drupal 8 ?

Sometimes we create the website but that is not quickly responded and we don't get proper users response on site. Sometime our client want to Speed Up the website and we just go through the Admin section and Aggregate CSS and JS files. But that is not properly working as our expectation. So here very first time we have some suggestion in easy way to Speed up the website and that will surly Speed up our website . That is tested with our projects. Please have a look suggestions for Desktop and Mobile both end..

Suggestions:
- Module to speed up site(Image Lazyloader, ADVANCED CSS/JS AGGREGATION)  --> We have added screen shot for checked options.
- Aggregated CSS/JS code.
- Remove extra CSS/JS that is not use full for front page.
- Set required custom image size(image styling) for page images.
- Create custom size of images(Home -> Administration -> Configuration -> Media -> Add image style).
- Follow Google page speed suggestion.
- Reduces Request to server.
- Uninstall extra modules.
- Use Optimized Image.
- Use critical css only ,use only those css/js which you need most.
- Add Async and defer attribute.
- Eliminate render-blocking resources.

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