"Faces" frontend speed improvement

[Dymirt]

Is your feature request related to a problem? Please describe.
I found that's frontend page 'faces' is fetching all photos for all faces, but shows only one smal pic of this person. May be there is an opportunity for a speed optimisation? Fatching only one main image of a person, and fetching the rest inside person page?

This is log from my terminal. Just to display a single person face I need to wait until 1235 files will be loaded.
[Debug] [DEBUG] photos: [FetchFacesMixin] Fetched 1235 new files: – {0: "99030", 1: "99159", 2: "99160", …} (photos-main.js, line 2)

Describe the solution you'd like
So I checkt, those files fatching is two times, one when loading 'faces' page, and one when its display photos per person. So there is a real opportunity, just removing fatching all files from 'faces' main page, and fatch only 1 pic per face. The problem seem to be in photos/src/mixins/FetchFacesMixin.js

[joshtrichards]

See #1411 (I think)