Misc DS Download Play lag

[Oron Gefen]

When connecting 8 dses on the same Mario Kart, I'm experiencing quite a bit of lag.
I was wondering what can cause it and what exactly can I do to fix some of it.
Some info you'll maybe find useful is I'm using 4 DSLs 1 DSi 1 3DSXL and the main console is a N3DSXL which runs the original Mario Kart
and I'm using a rom, not the original cartridge.
Thanks for anyone who replies.

 

[Yepi69]

Are you using a flashcart? If so, which one is it?

 

[Oron Gefen]

Are you using a flashcart? If so, which one is it?

an R4i with a kernel from this post
https://gbatemp.net/threads/r4-stage2-twl-flashcart-launcher-and-perhaps-other-cards-soon™.416434/
but I tried with an R43DS with the latest update aswell and still alot of lag