Indeed, I could replicate your issues after creating a few more events with pictures of them.
The Media library takes up to 15seconds to load 8 pictures. I’ve added the same pictures to all events.
At the first view, it seems that problem is related to files Relations.
GET /events → 5 seconds response time (10 events)
GET /upload/files → 15 seconds response time (8 pictures)
If I restart strapi after creating events & pictures, it gets back to normal.
After strapi restart:
GET /events → 100ms response time (10 events)
GET /upload/files → 20ms response time (8 pictures)
We will look deeper into this case to have a bit more information about what’s happening to open a bug issue.