To optimize performance of your website, you can use some plugins, that we recommend.
Pages Caching
We recommend to use WP Super Cache plugin:
This plugin will generate static HTML files from your dynamic pages.
Styles and Scripts Minification
We recommend to use Autoptimize plugin:
This plugin minimize and concatenate your CSS and JS files, so the page loads faster.
With this plugin you can enable images Lazy Load feature, that will also speed up your site loading time.
WP Rocket
As a paid alternative to WP Super Cache and Autoptimize plugins, you may use WP Rocket plugin, which may minimize your styles and scripts and cache pages.
CDN
On all our sites we use CDN provided by Cloudflare service, which is really easy to set up and provides caching and CDN.
Google PageSpeed Insights
Google PageSpeed Insights score depends on many factors, such as server and plugins configurations. You need to spend some time to optimize this.
Follow instructions, that Google provides you and keep in mind, that these scores are just recommendations.
If you check most of the sites (including best sellers among ThemeForest themes), you’ll notice that they hardly get around the 50s. Just make sure your content is great and you will surely get your visitors.
Some resources, that tested in 2019 September: