Hello, my friend,
A lot of page speed analysers do not actually run your website like real browsers, they simply analyse the HTML code and provide useful, yet very generic, insights. One tool I really recommend is https://webpagetest.org/, because it is using real browser in real machines and under real network conditions.
However, I do see that your images are being served with an Nginx header and, although the Adaptive Images plugin seems to be working, your images are still not being resized. So, one thing I need to ask is how exactly are you using Nginx?
If you are using it as your main server, then you must make sure that you have added the special code required to the server configuration file. You can see this code in the confirmation message after you save the Adaptive Images plugin settings.
But if you are using Nginx as a caching server, then this is an entirely different situation! Caching servers (and CDNs) provide a protective screen between your website and the rest of the internet and handle the image requests themselves. We can only handle this situation in an experimental way, which you can enable by setting the CDN support property in the plugin settings page.
Let me know how it goes!
Cheers,
Takis
