A sharp drawdown fps (The Amazing Spider-Man)

My PC:
CPU: i5 4690k 3.5 ghz
Graphics card: gtx 960 4gb
OP:16gb ddr3 1600
HDD: WD 1T
When I fly on a spider web in the city , the constant fps jumps from 60 to 30, 35, 40. How can I fix it ?