Name of Internet Service Provider (ISP)
Free
Country of residence
France

When does the problem occur (e.g. only during specific times such as in the evenings?)
At all times, worse in the evening.

Frequency of problem (e.g. every 2 minutes)
Every minutes if not worse. (1-2 lag spike per minutes from a test)

Game content in which the issues occur (e.g. dungeons, trials, certain areas)
Everywhere.

Others Informations
In my case, I've been having this issue for maybe 2 month, I know it's not because of the new servers but maybe if someone else is having these issues, it could help. From multiples route tracing, it seems like the issue comes from Level3 and Cogent.