You may want to take a look here: http://community.killzone.com/t5/Killzone-Shadow-Fall-PS4/bd-p/bEN_KZShadowFall
I've had a blast on the mp (the first online mp I've ever played), but it's been laggy as shit the last couple of days after the latest patch. I don't know if it had anything to do with Japan coming online or not. I've almost never had a problem (after 700+ games) until now, so I'm hoping this problem is short lived.
Looks like the developer (Guerrilla Games) was listening to the complaints and have fixed/are fixing the lag problem. It's always nice when a dev. will actually communicate with their customers...esp. after just a few days of problems.
Now that a week has passed since the release of 1.10 we have collected enough data to conclude that the lag did indeed increase. Because of this we have updated our servers this morning and rolled back the change we did to reduce the amount of network errors.
We're really sorry that this happened and we'll continue to monitor the lag statistics to confirm it is back to the pre 1.10 level.
Note that we're still working on improving the lag and there are a couple of changes underway.
Can't play right now, I can only get one match in before I get disconnected with Error 10100. The problem is my modem which has a strict Nat cone type or something like that. Many others have also reported the problem on the internet who are using my exact modem.
There's a fix but it's an expensive one... and that's to buy a new Modem all together lol. Just bought one online for $140, but hey it's worth it so no other games become unplayable because of my Modem.