If you have a high refresh rate screen, try setting a frame rame limit in Settings -> Video. Otherwise the game will try to draw as quickly as your hardware permits, and you might not need that.
For lower refresh rate screens, make sure that you have V-Sync enabled in Settings -> Video.
If your monitor has a high resolution as well, you might also try reducing Settings -> Video -> "Resolution scale", which will cause the game to render the world at a lower resolution, thus decreasing GPU load.
If you're playing on a laptop, it might have additional power and performance settings, for example Armoury Crate for ASUS laptops lets you set presets like Silent, Performance and Turbo.