Website loading very slow > change of format

Hi,

The last couple of days my website has been loading very slow when accessing it from the front end. When it eventually loads the format has changed (please see website using link above). Could someone please advise what is causing this and how I can fix it?

I have been advised not to update updates straight away due to this sometimes causing issues with your website reverting back to an old version. What are your thoughts on this and is this the cause of the issue?

All help would be very much appreciated.

The page I need help with: [log in to see the link]