FPS Drop at Domain of Istan

I have FPS problems near the Champion's Dawn area.Close to the Mastery Point.

Every time I am "looking at" the tower. FPS drops from 28~30 to close to 13.

Checking the Graphic options, this FPS drop seems to be caused because of "Reflections".Settings it to "All" drop my FPS to 12. Setting it to "None" or "Terrain and Sky" raises it back to 24.(When NOT staring at the tower, regardless of setting, my FPS stays at 28-30)

Full Brieffing::

• Happens since the first day the map was launched. Weeks later it still happens. Only tested during "daytime".
• Not in group. Happens regardless of the number of players on screen.
• Map Domain of Istan. Close to the mastery Point at Champions Dawn.
• Character used for testing: Souls Sin, level 80, Human Female, Thief.
• Last test: 05/03/2018 around 19:40 server time.
• Reproductive steps: Just approach the tower where the mastery point is.
• CPU: Intel i5 3570k (not OC'ed), GPU AMD RADEON R7 370 (updated). 8gb RAM DDR3. I am using the 64 bits client*.
• Never noticed this in any other map.

*I was a tester for the 64 bit client back when it was still optional. Tough nowadays its official, mine was downloaded separately back in the day. Can't say if that makes a difference.