Not only page speed. There are also more important things. Like content being too big for the screen (having to scroll left and right), text too small to read, clickable elements too close together and having annoying popups.
You can test your site's mobile friendliness here ..
https://search.google.com/test/mobile-friendly
I spent a whole week tweaking things to get a perfect score.
Now that 43% of online sales are via mobile and set to rise to over 50% by 2020 ... it's time to think "Mobile first" rather than "Desktop/Laptop first" when it comes to site design and layout.
... and KILL those damned popups!!! They're REALLY bad on mobiles.
