Specs:
fx 8320e 3.5Ghz
Gtx 950 ftw 2gb vram
12gb ram
I am having some fps drops(from 60 to 47) in some areas like the parade mission and the freeroaming mountain mission, this happens if I have any shadows turn on no mater the quality. And in the free roaming mountain mission the wall run drops fps for aome reason.

Same here, having frane-dips no matter what setting i'm using.
My specs: FX8350@4.0ghz, 16GB RAM, GIGABYTE Radeon HD7970 3GB, Windows 7 Ultmiate.
Pedning between 60 and 42.

On my 2nd PC there's no such problem though.
Specs: i7 4770k@3,5ghz, 16GB RAM, GIGABYTE GTX 780 3GB, Windows 7 Ultimate.
Silky smooth gameplay. I've even locked the FPS to 48 to get "a game-ier look".
No problems at all.

So... it's maybe a AMD related problem. It's just my speculation.

You don't need to turn off all shadows, but try to turn off the "detail shadows" option.
They're extremely expensive on the CPU, especially if you're playing in co-op mode.

If that doesn't help you can try to tweak the texture streaming by editing the INI settings.
I found the texture streaming is set up way to heavy and the game doesn't even use a quarter of my available VRAM ...