Have you tried enabling lazyload, I get great page speeds now lazyload is added. Try the Main Blocs site in google speed check.
It's also important to note, Page speed is not always about the code but also about server optimaztion and server quality.
Do you have gzip enabled on your server, have you set the cache length for images, CSS and JS to 1 week? Are you using DV hosting or cheaper shared grid hosting, are you using a CDN to handle larger files like videos?
Page speed has many factors, the actual code is usually not the biggest factor, the hosting quality is.