So when ever i go inside of building my game lags so badly like 10fps outside i get like 15fps i have no idea why i am so laggy here is my pc specs i have lowered the settings and changed them over and over any help would be nice.

i5-4460 cpu 3.20 GHz processor

8.00 gb ram

64 bit

Nivida GeForce GT 720

Your video card is well below the minimum required to run Fallout 4 well.