We talked about benefits of cache plugins before now we are going to talk about proper setup of WP Rocket plugin or briefly Rocket.
Go to Settings → WP Rocket, here are WP Rocket options.
Lazyload: It defers images, videos and iframes loading. Huge impact on loading time. Publisher has lazy loading itself. Use one of them to avoid conflict.
Also in every post you can find a metabox which you can disable these options (and some other options) for every single post/page.
User Cache: Logged in user cache is useful when you have a membership site, or similar when users must log in to see content. Read user cache on Rocket doc if you are using a plugin for login/logout in WordPress.
SSL Cache: Enable it if using SSL. Sometimes you might have SSL and non-SSL content. This gives you the ability to turn off cache for SSL pages.
Emoji Cache: Every tiny emoji sends a HTTP request and take time to load from WordPress server. Cache them for avoiding this delay.
Embeds: Prevents other sites from embedding your content on their website. This is useful for preserving bandwidth and your content owning.
Cache Lifespan: Select a period for refreshing cache. If you do not update website content frequently, select a large period.
2- Static Files
Options in this page should be tested on your website. There is no guarantee they work fine on your server configurations.
Minify Files: Reduce size of files. If you enable these, you can find options in every single post/page for disabling.
It’s a frequent problem that one or some files have problem with minification. In this case, you should find problematic files and exclude them from minification. You can read this thread about Find the right JS files to exclude from minification or just exclude all files from minificarion then include them one by one. If you choose the last, after including every file, refresh your page (purge cache plugin and browser cache first) to see if the problem is back. If it’s back, this file is problematic and must be excluded; if no problem, there is no need for excluding this file. File excluding is in Advanced tab.
Also the problem might happen with CSS files. The procedure is the same as JS file; exclude all files and find the problematic ones by trial and error.
Combine Files: Test it on your website.
Remove query strings: Remove query strings from static files is usually mentioned in GTmetrix.
Render-blocking CSS/JS: Good options if they work fine.