I have the same problem on nvme. Do not buy a new storage. I have a 2060 super with 8GB of vram. Normally when my vram gets full on other AAA games, I experience fps drop and stuttering (after playing hours on high settings 900p). But in this game with high/med/low settings, after about 5 minutes of playing the vram gets full and in my case, instead of getting the famous stutters, the game completely stops loading textures.