I had given up playing DS2DE because of horrible stutter I get throughout the game.

had Tried pretty much every solution there was but nothing worked.

I recently upgraded my PC

My previous setting was Phenom and GTX960.
Now it is Ryzen1500x and GTX1070.

since I upgraded my pc, I just thought i should give DS2 another try, and now I see the game works flawlessly.
No stutter whatsoever.

I wonder there has been a new patch or is my PC just overpowering the horrlblly ported game?

I think it's your new set-up is able to handle the game better and probably it's badly optimized or the system requirements are bullshots; I have a GTX 750 and AMD FX-4350 and the game can barely run past 30 FPS despite what the recommended requirements say. Meanwhile on a different computer with a GTX 1060 and AMD FX-6300, it plays flawlessly and beautifully at 60+ FPS, on par with the first game's remaster on my computer (although the first game's remaster was done by a more competent dev team).