Admin side slow-down (Grav 1.7)

I'm building a site for a vintage designer items shop and it's now running on Grav 1.7. This weekend the client went to put some new items up and today the admin side has massively slowed down, to the point that I'm getting 500 errors.

I've checked the server and it's not overloaded - what should I check in Grav?

I'm not sure where any useful logs might be. I've had a look at what was uploaded and there's nothing out of the ordinary. I have a local version of the site and it loads very quickly - as this one has until the weekend.

All tips appreciated.

@dan-james, Have a look at this blog item on performance, Grav 1.7 and flex-pages. Scroll to midway the page to get to the performance part.

@

I have no idea how many pages have been loaded and that is what the blog is about...

if "lazy loading" fixed your performance issue, please mark your post as solved.