User blog comment:DynamitMC/The Reasons Why A Teitoku Fails to Do A Certain Map/@comment-50.27.23.77-20150905060719/@comment-26224833-20150906012240

probably because in Japan, summer event concide with summer vacation, so more people playing than usual everyday. Maybe that's also the reason why they made summer event as a large-scale.

So with large-scale event on hand, and many people playing because of vacation, might be the reason why in summer some servers became unstable

CMIIW