I'm confused because Maru himself said that heavier geometry = RAM usage increase. A geometry heavy scene uses more RAM than a geometry light scene. I'm looking at this from a wider perspective than a single chair.
That's right, more polygons, equals more RAM, but what i'm trying to tell you is that in most cases displacement produces much more polygons, than turbosmooth. Let's say you have two chair models, one of them has 50 K polygons and the other has 2 M polygons. If you apply the same material with displacement on them and both models will be at the same distance from the camera, then at render they'll have virtually the same polygon count and will use the same amount of RAM, but the one with 2M real geometry will be much less prone to artefacts and if you will turn off turbosmooth in viewport, you won't be paying any performance penalty.
It's kinda hard to explain the nature of these artefacts in words, so i draw a picture. Maybe it will helps to explain why this is happening and why higher turbosmooth iterations are helping.