Rekordbox Slow and Lag

Hello dear moderators.

I encounter the following incident:

Since installing version 6.0 of Rekordbox with my DDJ 1000, I have a huge machine slowdown,

I have tested the following:
- Reduces graphic elements,
- disconnect any optional devices or adapters
- reinstall my Mac (Clean install)
- with the songs on the external hard drive (SSD, HDD LaCie, HDD WD was tested)
- with the songs on the internal hard drive (SSD Drive)

I tried to put my old version of Rekordbox back which worked better,
but, following the update on Big Sur (which I know should not be done)
(but I already had the problem under Catalina ),
version 5.8.5, crashes as soon as I go to setup.

It looks like an information transfer problem with USB C, because since the update,
I have regularly disconnected my equipment. (I also did the cross test with another computer)
Do you have a tip, or a manipulation (that I might not have done)

Material Information :

Nom du modèle : MacBook Pro
Identifiant du modèle : MacBookPro13,2
Nom du processeur : Intel Core i7 double cœur
Vitesse du processeur : 3,3 GHz
Nombre de processeurs : 1
Nombre total de cœurs : 2
Cache de niveau 2 (par cœur) : 256 Ko
Cache de niveau 3 : 4 Mo
Technologie Hyper-Threading : Activé
Mémoire : 16 Go
Version du programme interne du système : 429.80.1.0.0
Version SMC (système) : 2.37f24