Causing Site to load slowly

My site has started loading very slowly, and the errors seem to be generated on every page load from dashboard, when checking with Query Monitor plugin I get the following errors (screenshot: https://www.dropbox.com/s/looob3bb6srzo9g/screenshot-particularsart.com-2018.04.03-15-18-42.png?dl=0)

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