The default configuration in the compose file seems to prefer having different volumes for the downloads and library directories.

ex for SONARR:

- ${DOWNLOAD}/complete:/downloads - ${DATA}/tv:/tv - ${DATA}/anime:/anime

For me with both the downloads and media library on the same drive this caused huge performance issues when the apps postprocessed the files as it causes them to copy the files between the volumes instead of recognizing it could hard link them instead. Changing to have a single data volume and referencing the paths below them in the app config allowed near instant moves.

Its also mentioned in the Sonarr docs:

https://sonarr.tv/#downloads-v3-docker

Most Docker images suggest paths like /tv and /downloads. This causes slow moves and doesn't allow hard links because they are considered two different file systems inside the container. Some also recommend paths for the download client container that are different from the Sonarr container, like /torrents.
The best solution is to use a single, common volume inside the containers, such as /data. Your TV shows would be in /data/TV, torrents in /data/downloads/torrents and/or usenet downloads in /data/downloads/usenet.

I recognize everyone might not have their download and media library on the same mount, but if you do this is a vastly faster way to configure it.