Simple 3D model all of a sudden uses too much RAM (in viewport or render)

Hello, I have this 3D model which has only 768 faces. It has one material with plenty of 8k textures in it. Everything worked good at the beginning but now I started having memory jumps of like 44GB of RAM. It is due to heavy material with textures (blend.file is of 1.25 GB in size). In the past everything was working properly but now I started having very big memory spikes which causes blender to crash. In the past, just this one small hill took less than 8GB of RAM with adaptive displacement turned on, now everything is turned off and yet the RAM climbs up to 44GB of RAM

I have 32GB or RAM
GPU is RTX 3090 24GB

I Have this image from the past which shows that everything worked properly, I changed nothing considering this first hill (at which all of those blue shirt people are standing on).
Now even if I separate that hill individually in another blend.file, everything just crashes.

Although when I drop all the textures down to 4k, then everything is good. But I don’t understand why are RAM’s increasing and decreasing and not VRAM. Texture size should affect VRAM and not RAM, I don’t understand.

Are your people duplicates or instances? You want instances in this case

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Some of them are duplicates and some of them are instances. They don’t matter now, because the blender crashes with only one hill in the scene (without people in it), even with just the hill in the separate blend. file everything crashes.

Why do you need 8k textures?

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  1. Disable adaptive displacement. Bake full resolution mesh to 4K normal map and use 4K diffuse map, and use something like 512x512 displacement mesh for hill.

  2. Use 4K textures.

  3. Instance those people and other meshes that repeats.

  4. If you have HDRI, use 4K version of it in environment and render background as separate pass from high resolution version.

With these simple optimizations, it should fit easily to some 512Mb VRAM or RAM.

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