Hi,
I would suggest doing a clean install of the graphics card driver that may help in solving the issue.
- Start by uninstalling the Nvidia graphics driver from Device Manager.
- Next is to uninstall anything related to Nvidia from Programs and Features.
- Once done, download and install the latest driver.
- Here's the link: nvidia.com/Download/index.aspx
- Reboot your laptop once the latest driver has been installed.
- After the reboot do test your laptop again and see if the same problem will persist.
- If the FPS will still drop do check the temps of your laptop while running the game because it can also be heat that causes this kind of issue.
- You'll need to clean the inside of the laptop and apply new thermal paste on both GPU and CPU.