First I would like to explain that a website speed does not depend upon a theme only. The media type (images+videos), server and plugins or any custom code used on the site also affects the performance. I see your score is very low and it is no because of a theme here but because of the CDN, it does not work or needs to be configured.
Please go to the waterfall tab of the above link and you will see the resources taking time to load. The CDN seems to be preventing the loading of other important resources like theme resources. I would suggest you please first set up a cache plugin and use an image optimizer plugin. Your image size should be in KBs.
Please follow the docs setup your plugin and check?
While setting up these plugins please deactivate CDN and then check, it will surely improve the website and please contact your host and ask them to check if the CDN or nitro pack is setup correctly.
Please let me know so I will test it again and guide you accordingly.
