1. Deactivate all unwanted plugins
  2. Latest Version of WordPress and All Plugins
  3. Use PHP 7
  4. Block Bad Bots and Crawlers eating your server resources
  5. Reduce the size of the images
  6. WordPress Caching
  7. Always Use CDN for uploading video and Audio files
  8. Optimise database queries from your theme
  9. Disable Hot Linking
  10. HTTPS for all pages
  11. Use a Web Application Firewall at DNS Level
  12. Reduce Post Revisions