Samba perfomance issue; write access lookup too slow?

[Mortis]

Hi,
I am currently having some trouble with NAS read performance when accessing files from another user. I described my problem in the official QNAP forum, but hope to reach some more people here that might have experienced and solved this issue since I believe this migth not be QNAP specific problem.

Thank You for any helpful input,
Magnus

PS: In case linking the QNAP Forum is not wanted I can also copy&paste my post to this forum.