Takes very long to open large directory

Submitted by hei..@..il.com

Assigned to Stephan Arts

Link to original bug (#13102)

Description

When I open an image in a directory with >30k other images, Ristretto takes a long time until I can interact with the sidebar in a useful fashion.

It appears that the process of finding new files even slows down as more and more files are added to the list on the side, in the beginning it's more than 1000 files per second, in the end, it's less than a hundred files per second.

Would it be possible to put a list of placeholders for each image before further processing?

Actually measuring some times, it seems that it takes:

5 seconds for the first 10000 images. Another 20 seconds for the next 10000 images. Another 45 seconds for the next 10000 images.

This looks a bit quadratic, maybe it could be done in linear time?

Version: 0.8.1