All linux based NAS have the same problem with small files, 56 KByte are small. It’s a bit tricky to explain the background but I try my best:
Opening such small files is not an issue but saving those files.
The file itself will be written to the share, then afterwards the operating system changes the user rights (chmod) and the owner (chown). This three-steps-process is valid for all kind of files but the smaller the file is, the bigger is the so called system overhead. That’s unfortunately a fact and cannot be changed.
A possible solution would be to “clean up” this folder by creating several sub-folders to reduce the overall amount of files.
For example, David Tobit software runs a single folder with hundredthousands of 1 Byte files inside; this is a nightmare for any NAS on this planet