Originally Posted by
Umbrasin
Animation delay, cast times, and effect resolutions are unrelated to the tick rate, odd as that may sound. Tick rate refers to how often the server updates your position (x,y coordinates), which is not the same as what you see on your screen (where you see yourself). In practice, the server can be up to 0.3s “behind” when a mechanic resolves. That small window can easily determine whether you’re considered inside or outside of an AoE marker, or whether you succeed or fail a mechanic.
As for sources, both XIVAlexander and ACT interact directly with FFXIV's network data. ACT, for example, sniffs network packets to record exact damage, healing, timestamps, etc. This is why eight people in the same raid will all generate identical logs. Analysis from both tools shows that while the server tick interval can fluctuate slightly, it consistently averages around 0.3 seconds. Regardless of whether the tick rate is exactly ~0.3s or not, the point is that its current speed is incapable of keeping up with the faster encounters introduced in Dawntrail.