Look at the state of the forums.

[Rae88]

As an example, JP has 3 data centers. EU has 2.

Back in July EU had about 60% of the active non-free trially characters compared to JP according to luckybancho. That gap closed recently but EU has traditionally had much fewer players than NA or JP I believe. According to the latest LuckyBancho NA's population has exploded. It's not to dismiss the issue but when according to the latest Lucky Bancho NA has over twice the number of active characters as EU and still has 3 data centers, something bigger is the problem than just the number of data centers EU has imo