ACD slow download start

I have an ACD folder with 350k+ files. Whenever I do a rclone move amazon:/folder/file . it takes 1h+ to start the file download. The files size range from 200kb to 20mb so the download is fast, but starting the download is terribly slow.
This doesn’t happens when I do the same cmd on a file that is in a folder with less files.
I’ve tried the --no-traverse flag but nothing changed.
Is there anything else I can do to speed up the files download?