whenever the camera automatically zooms in or out, the game starts to lag out for a fixed period of time. In my case, the fps dropped to 20 (this number is variable based on the system)
This looks like this:
This happens for example at the Shadow Behemoth fight, or plenty others. This is also an issue at giganticus lupicus in arah: when you enter the arena, the fov changes, and the game lags out for exactly 40s. In addition to that - more relevant to people than some old dungeon - it also happens in fractals (especially 99) and probably raids.
Basically any content, that contains auto camera zoom is very unpleasent to play. I confirmed this issue with around 5 other people on different system configurations. The fps drop is present on every system configuration: windows vanilla without addons, windows with arcdps, windows with dx9pxy (also on linux, but that doesnt matter to most players). One of my friends reported a drop from 120FPS to 70FPS. This is probably why this issue has gone unnoticed for so long. You only ever feel it at lower end systems or higher resolutions. I tested and reproduced the issue on any graphic setting (yes, I went one by one through every possible option and checked it. Also verified with different FoV options, also tried out the -oldFov startup flag).
Therefore it should not be hard for you to reproduce this issue, if you watch the fps number carefully.
Whenever this happens my GPU usage drops to around 70%, CPU-usage stays the same.
I could not find another thread or bug report on the issue tracker - I still hope I didnt create a duplicate.
Thanks for taking the time to read and investigate this issue.