Optimization on mobile devices

[Beshizume]

Hello

Like the title says, i have a serious problem with optimization of my web store. I can totally manage the process on "normal" site, but, probably because of the theme i'm using, the google page speed test gives an awfull number regarding my mobile version of the store. Any ideas, tips, maybe addons or modules that i can use to improve my situation?

 

Theme i am using: https://addons.prestashop.com/en/fashion-shoes-templates/16958-01-oslo.html

Prestashop version: 1.6.1.19