Pictures in the same folder or subfolders?

Question

Images

Hello!
Tell me how best to store images on the server.
1. There are users, let's say 10,000 users, each has an avatar, is
it better to store everything in one users
folder or split it into at least 2 folders of women and men
users / man
users / woman
or something else?
2. There are 10,000 posts for each post with 10 pictures for a total of 100,000 images
. Is it best to store them in the 1st folder
or split them by date or
by post title?
Because as I understand it, the load when displaying a picture will affect the speed!