1. What is Render?
The web browser engines render web pages. They use the DOM (Document Object Model). HTML is a source to load the DOM. The concept is separating the data from the view and if you ever used web developer tools in a web browser you can see an “Elements Inspector” and other windows with information.
When the script queue is very long, it can take a while before visitors are able to access your site. Often, many of these scripts aren’t necessary for viewing the website right away, and could just as easily wait to run until after the site itself is fully loaded.
2.Server-side rendering (SSR):
Basically all of your page’s resources are housed on the server. Then, when the page is requested, the HTML is delivered to the browser and rendered, JS and CSS downloaded, and final render appears to the user/bot.
3. Client-side rendering (CSR):
Of course, site speed is affected by more than just render-blocking scripts. That said, this a factor that can make a significant difference in load times. Remember that every resource on a webpage takes up bytes, more of which result in longer download times. The fewer and lighter scripts your site has, the better. After all, you don’t want to let a slow site negatively impact your business.
2. Properly call your css files
3. Do not use @import to call css
4. Properly label conditional css
Use less CSS files in the critical path