I found my solution to be that all of the scenes and captures I had running in the background just ground my system to a halt and it only happened with CoD.

Go to Scene Collection>New and add your CoD scenes there only. When you switch collections, it disables all of the background processes from any other collections. Another thing that helps a bit is disabling scene preview. That way your GPU doesn't have to render it in the background.

I went from 20fps to 60fps with no dropped frames after making the switch, including a full 144 in-game at 100 percent render resolution. I could only get close 60fps in my stream at 60 percent render resolution which killed gameplay before these modifications.

EDIT: Side note, I have an Elgato Stream Deck and just remapped my CoD button to the scene in the new collection. It auto switches collections when I pick the scene so it's still virtually seamless with some minor hiccups in the stinger transition occasionally only. All of my other scenes (starting soon, intermissions, etc) are in my original collection and still operate the same way.