Ever since the Season 4 update, I have been running into some strange stuttering issues in Modern Warfare.  It is most pronounced in Multiplayer, but also shows up some in Warzone.  In multiplayer, it seems to happen most when someone is nearby (which is precisely when I don't need a slowdown).
 
I can tell it is coming when shadows do not look right.  The GPU time will spike into the 20-40ms range (usually less than 10ms), and my FPS will go from the low 100's to the low 20's.
 
I have killed all startup processes that I was able to kill, and it did not help.  I made sure I'm running the latest Game Ready drivers (running 451.67)
 
System Specs:
Motherboard: Gigabyte Designare Z390 v1
CPU: Intel Core i9-9900k
GPU: EVGA RTX 2080 Ti XC Ultra (11G-P4-2386)
RAM: 4x Corsair CMW32GX4M2C3200C16 (DDR4-3200)
Storage: ADATA SX8200PNP 2TB, Samsung 970 Evo+ 2TB

This only occurs in modern warfare? If yes, it's clearly a game issue.

Grab the hotfix drivers, I had stuttering in a few different games that the hotfix drivers fixed.
https://forums.evga.com/Nvidia-45185-Hotfix-driver-m3066921.aspx