- image sprites
- Amazon CloudFront or Cloudinary/Akamai CDN https://wordpress.org/plugins/cloudinary-image-management-and-manipulation-in-the-cloud-cdn/
- https with Qualys A+ rating
- Database innodb, cleanup, missing indexes
- root files, icons
- http://zoompf.com/free
- https://www.woorank.com/
- Page URL-s with accented (non-ASCII) characters (pro, contra)
- Own virtual server near your visitors
- http://www.google.com/webmasters/tools/mobile-friendly/