Here are my specs,
Windows 10 Professional 64-bit (up to date)
16GB (8x2) HyperX Fury DDR3 1866Mhz RAM
AMD FX 8350 stock clocks
MSI Radeon RX 480 Gaming X 8G (19.4.3)
MSI 990FXA Motherboard (latest BIOS)
So I have noticed a 33.3% drop in performance in a few areas of Hitman 2 Silent Assassin. I have noticed it throughout the game so far, but will attach screenshots of a area affected in the fourth mission "Kirov Park Meeting" where I stand on the right side of the Church facing the area where the two generals meet.
In driver 16.9.2 I have a constant 64FPS (limited with Riva Tuner) and in driver 19.4.3 I have a constant 38-40FPS (limited to 64FPS with Riva Tuner since no in-game frame-limiting present with Radeon RX 480, but possibly triple buffering). Furthermore it might be related to the same issue as Unreal Tournament 3, so maybe it will improve with the new fix for Unreal Tournament 3.
Here are the screenshots,