Why is my PC lagging even when resource usage seems low?

It sounds like you might be experiencing some thermal throttling. Just checking the task manager isn’t enough, especially for your disk usage. You might want to look at temperatures of your CPU and GPU to see if they are overheating. Without more specifics, it’s hard to give precise troubleshooting advice, though!

If you're seeing FPS drops in games like People Playground, it could be due to the game’s optimization. Sometimes poorly optimized games won't utilize your hardware efficiently, resulting in lag, especially in scenarios where a lot of objects are spawned. Make sure you have the latest drivers and check that your display cable is connected to the GPU, not the motherboard.

Could you check if this slowdown happens at any specific times of the day? It could help identify if there's a pattern or something else going on. Also, if you simply open Chrome and see high resource usage, that's another clue!