Depending exclusively on the codecs I use, htop shows a CPU usage of 90-100% or 10-20%. So, I use those that don't require a huge CPU usage. Memory and Swap are not affected, as far as I know. But despite those circumstances, the outcome is the same. Recording with no sound = smoothness, 60 fps, recording with sound = choppiness, 10 fp5s.
Something I also noticed is that it also happens before I open Doom 2, so it doesn't matter whether I'm playing or not. Even with just the terminal and the file manager open.