My FPS will regularly (about 50% of the time) drop by about 80% and stay low after zone or anima leap. Stable peak varies by zone and conditions from 70~100 FPS. Stable low is 15~20 FPS.
Workaround: alt-tab out and back.
NB: windowed borderless mode, dx11, nvidia 1080, latest drivers. This bug has been present since I started playing a couple months ago, but I only recently noticed exactly when it would take effect and discovered the work-around.
I suspect some kind of race-condition in your post-leap/zone GFX initialization.