Date & Time: 7/29/2018
Frequency: Really often
World Name: Coeurl
Character Name: Sora Maxwell
Party or Solo: Party
In-Game Time: Always
Area and Coordinates: Mist, Ultimacy
Steps:
1. Log In
2. Play
3. High GPU and CPU utilization

GPU performance change before and after you started having the issue: Used to run at a smooth 60 fps on maximum settings. Now it runs at ~40-57 (upper end) on High(Desktop). Whenever I check utilization, my CPU is maxing out from XIV alone, and my GPU is high on utilization as well.

GPU: NVIDIA GeForce GTX1060 6GB
Driver Version: GeForce Game Ready Driver v398.36
CPU: Intel(R) Core(TM) i5-4690 CPU@3.50 GHz
RAM: 16gb
Hard Drive: SSD
OS: Windows 10 Home
OS Version: 1803
Graphics Settings: High(Desktop) (had to drop it to here from Maximum)
FPS Limit: (System Configuration > Display Settings > FPS Limit) 60