I use arduino myself. The KMBOX speed slider is default at 3, since I am running a Ryzen 9 9950X Full tower radar machine I was able to use speeds of 7 to 8 without issues when I was on the Kmbox. The slower the PC the lower the number, the bigger performance PC number goes higher if you wanted. But if 3 seems slow to you, try 5 to 6.
Also if possible use Wired connection to the XIM over bluetooth. Bluetooth can be interfered with other devices if your close to microwaves, WiFi boosters, etc. Wired is always King. Bluetooth is a slower connection.
It wouldn't be any of that, it works perfectly with other products. I've just recently switch from a full tower to micro PC but it was having the same issue before. Hopefully they just fix it in the future, seems to only be for Xim/Controller emulation. Works fine with just M+KB aim.