Consistent rhythmic frame drops followed by recovery, repeating in a continuous cycle

[Arrhin]

There are more bottlenecks than CPU/GPU. FFXIV often likes to explore these. I expect what you (and many others, yours is not the first post regarding this) are seeing may be network (On SE's side) related. I'm not seeing these issues personally, just thought I'd weigh in on both a potential cause, and the legitimacy of the issue.

[EX_WhiteDragon]

Indeed, the engine used in this game is really outdated, which may have caused a lot of chaotic issues. Personally, I suspect that the problem is related to frame generation, such as a lack of true synchronization with the monitor's refresh. I don't have a deep understanding of this, but I hope that SE's programmers can make an effort, although this problem has persisted for at least a few years without resolution, which makes me quite pessimistic.