Rekordbox 6.03 (and every 6. version) very SLOW with related tracks on

Hi, i'm a professional DJ using RB since day one. Since 6.0 i've huge troubles with speed. Especially if i have the window "related tracks" open (and this is one of the main extras from RB!!! i'm using it all the time). If this window is open, the browser needs around 4-8 seconds to find songs in my library. 
If related tracks is closed, it works fine. 

Latency is on 12ms, all the stuff like "lighting" is deactivated.
I'm using a MacBook pro 15", 2017, 16RAM, 2.9 GHz Quad-Core Intel Core i7 with Catalina (this is not the problem).

Is there a solution for this? RB isn't usable like this. 

Thank you for your answer.