Why is Saints Row IV dropping from 80 FPS to 20 FPS

[Enemy of Islam]

My specs are

AMD A8 5600K APU

AMD RADEON R9 270

16 GB RAM

Windows 8.1

I run the game on Ultra but it also does it on the lowest settings as well, it was usually go from 80 FPS to 40 FPS then on occasion down to 20 FPS. When I'm high in the sky it has high FPS but when I'm sprinting on the ground or fighting lots of enemies it drops to 20 FPS. Why is this?

 

[azathoth]

This sounds like it would be due to CPU usage.
The detail settings between Ultra and Low don't really change the CPU's load much at all, they effect the GPU which is the much stronger part of your system.

When you are sprinting, a lot of new buildings, npcs and more are being quickly loaded into the game requiring CPU resources. Same with fighting lots of enemies, tons of CPU calculations going on there.

That being said, the 5600k should be able to handle SR4 better than that even during peak settings I think.