Need to perform below steps for increase a speed for Magento 2
- Upgrade Magento to the latest version.
- Enable Varnish Cache.
- Set flat categories and products to increase the read speed of the database.
- Reconfigure JavaScript and CSS settings.
- Set up Content Delivery Network (CDN).
- Optimize images and themes.
You can use Speed increase extention for Magento 2 from here:
https://amasty.com/google-page-speed-optimizer-for-magento-2.html
