Low FPS in League of Legends

Dear People of CHF,

Recently while playing the video game League of Legends, I've been getting 20 - 30 FPS when I used to get a solid 60 FPS.

I've checked the help forums on their website, all my graphics drivers are up-to-date, I have cleaned out my registry, and I've reinstalled the game incase there was corrupt files. Nothing has helped the FPS problem.

I was wondering if anyone has any idea what could be causing this FPS problem.

These are my specs:
Operating System
Windows 10 Home 64-bit
CPU
Intel Core i5 @ 2.30GHz
Skylake 14nm Technology
RAM
8.00GB
Motherboard
Dell Inc. 0H87XC (U3E1)
Graphics
Generic PnP Monitor (1920x1080@60Hz)
Intel HD Graphics 530 (Dell)
4095MB NVIDIA GeForce GTX 960M (Dell)
ForceWare version: 375.70
SLI Disabled
Storage
238GB SanDisk Z400s M.2 2280 256GB (SSD)
Optical Drives
No optical disk drives detected
Audio
Realtek Audio