As most of you are probably aware, the Xbox 360 release of Persona 4 Arena has had some issues with its netcode. The problem was first noticed when 360 gamers in Japan experienced unusually high levels of latency compared to their PS3 counterparts. The North American version of the game released earlier this week also experienced the same issues.
However thanks to the development team working hard to fix the issue, a patch has already been released to both Japanese and North American versions of the game. From my experience with the title it seems to have fixed the issue as online matches now flow smoothly compared to how they were working just a few hours ago.