MxMC - Problems with unresponsive playback

Greetings!
We are trying to solve problems with slow and unresponsive playback in MxMC. Sometimes we have to wait for more than 30s for MxMC to fetch the video. We use 10x QNAP 8 bay NAS on the different locations, but the network connection was tested and it should be fine.

Can anybody share some tips or tricks which would help with MxMC performance?