WP fastest Cache

Hi – I am using WP-Fastest cache. I am very new to this so please forgive my ignorance, lack of understanding.

I have found the site loads faster with this plug-in but for some reason today, when testing the site – going through the various pages, when I click back to home page from the navigation bar – the home page seems to freeze. If I refresh, the page loads – otherwise it just hangs blank. Any help on this would be greatly appreciated.
website URL for reference is : https://www.mccarthy-group.co.uk

Thanks