Slow PageSpeed

Hello!
recently we tested the theme through the google Page Speed Insight.
The result is really bad especially for mobile version.
https://developers.google.com/speed/pagespeed/insights/?hl=ru&url=https%3A%2F%2Fpelicanbikerentals.com%2F&tab=mobile

We tested it even without photos (switched them off) as well and the situation is the same.
I think there is a theme problem or plugin problems. Not sure really.
As you have better understanding of your theme code and used plugins please help us to improve the speed.
Thank you!