Sudden FPS drop in multiple games

So, I've been getting pretty good framerate on most of the games on my new laptop. A couple days ago, I tried playing Minecraft modpacks which had some major problems. I tried to fix those, which resulted in, well, them not being fixed. Now, my FPS in most games is quite bad compared to what I was originally getting. Some examples are World of Tanks (used to get 60 fps, now struggling to get 30) and The Binding of Isaac: Afterbirth (had some minor framerate issues which are now more severe). My PC's basic specs are as follows:

CPU: Quad-core Intel i7-6700HQ

GPU: Nvidia Geforce 960M w/ 4GB of dedicated video memory + integrated Intel HD 530

16GB RAM

OS: Microsoft Windows 10 Home

I currently have the "Preferred graphics processor" set to "High performance Nvidia processor" in the Nvidia control panel, but that seems to have no effect. Additionally, I have uninstalled and clean-reinstalled the latest drivers and reset both the global and Java settings in the control panel.

I ran MSI Afterburner during a battle in World of Tanks. What I saw was that I'm not using up all of my GPU's processing power (average: ~60%). Last time I checked, no power settings are limiting performance, so I have no idea what it could be.

Is there anything else I could possibly do to try and fix this issue?

EDIT: Lowered WoT graphics settings and saw no change in average framerate, as if it's almost locked at 30fps.