Why is the speed of my post slow on mobile?

Hello, I was using Wordpress but I decided to use Ghost for the speed of the website. I’m using Google Pagespeed Insight and the front page returns 90+ on mobile and desktop. But when I analyse a post, mobile returns 45 (red) and desktop is alright with 90 (green).

Is it normal posts on mobile are slow? Is there a quick fix to solve this issue?
Many thanks

It seems disqus was slowing the posts on my blog. Now I have a button to load them if the readers request them.