Why is it slow to open pictures via Webdav through a domain if there are a lot of files in the folder?

Question

CentOS

I mounted a megafon disk (I also tried Yandex disk) to vps, in Nginx I created a rule to open pictures through my personal domain.
The problem is that when you try to open a picture domen.ru/kartinka.jpg, the opening takes 5 seconds.
If you access the Webdav directory where there are 10 pictures, the picture opens instantly