Track loading time on CDJs over rekordbox pro dj link (on laptop) very slow

Hello,

I have the following problem: my 2 CDJ-2000nxs as well as 1 DJM-900nxs are connected via a gigabit switch via LAN (Cat6).

If I now connect my desktop PC (Win10, i9-9900k, 32GB RAM) and rekordbox 6.7.5 via Pro DJ-Link, select "rekordbox" as source on my CDJs, the songs (MP3s) including hot cues are completely loaded onto the player within 3-4 seconds.

If I now switch to my laptop (Win10, i7-7700HQ, 16GB RAM) with rekordbox 6.7.5, loading the same songs including hot cues to the same CDJs takes between 30-35 seconds?!

The laptop is running at "maximum performance", WLAN, Bluetooth and virus software are turned off or closed. 

A normal file copy from the network using Windows Explorer runs at 113 MB/s.

What could be the reason for this difference? Have I forgotten a setting on my laptop?