Wrong default value for background threads on Windows
On my system setup darktable is configured to 'background threads' to 1 after install. I experience very poor performance when handling thumbnails in folder with 1000+ images (from spinning harddrive). The interface can become unresponsive - especially if exiting the application. Changing 'background threads' to a higher number gives much smoother handling of thumbnails.
The user manual https://www.darktable.org/usermanual/en/core_options.html says:
NUMBER OF BACKGROUND THREADS
This controls how many parallel threads are used to create thumbnails during import. On 32bit systems it is strongly recommended to set this to 1. Needs a restart if changed (default 2).