This has almost nothing to do with a NAS.
I'm loading my UHD BD from a encrypted mount share from google drive.
Today I took the time mounted my share on windows with rclone and verbose to see what the hell was jriver doing.
Well, it has a really erratic read pattern.
The problem is, jriver reads a portion of index.bdmv later the clpi and keeps going back and forth each other. Instead of actually reading those small files, putting those on ram for quick access and actually reading directly from the file for large files.
Here's the log of it's access:
https://pastebin.com/uT0n2TZ8This goes unnoticed for regular access but it's a waste of resources and movies could play much faster.
Actually I'm unfair to jriver, maybe it's a windows thing, but it would be great if some dev could look into it.