Expanding section extremely slow on opening

Hi All,

On our training page, towards the bottom, we have expanding sections that expand to show training courses within the section.

Up until recently, these sections expanded with no issues however in the last few weeks we have noticed there is a lag to the content within rendering and displaying - particularly the ‘Specialist Application’ section which has the most content.

Would anyone have any tips as to improve this or be able to explain why this could be?

Thanks in advance!

Here is my public share link: LINK
(how to access public share link)