sharedmesh using memory ?

Hello,

Im have a little question regarding sharedmesh's memory use.

Situation : Im making a grid-base map system, quite like Dwarf Fortress, except 3D. The way I do it is as follows : 1) Generate terrain data for the map, 2) Procedurally create mesh chunks - each chunk cover a small area of a level - and keep mesh chunks in memory, 3) When a level must be displayed, I assign the chunk meshes to existing gameobjects using sharedMesh.

What happens : The first time a chunk mesh is applied to a gameobject renderer, I see a memory usage increase (arround 12MB).

I assumed that since the mesh already exists in memory, aplying it as a sharedMesh should not increase memory usage. Am I wrong or did I do somthing inappropriate ?

Code called when a level must be shown :

for (x = 0; x < chX; x ++) {
for (z = 0; z < chZ; z ++) {
for (y = 0; y < ml.showLevelBelow; y ++) {
    if (lvl - y >= 0) {
        chunkDisplays[x,y,z].active = true;
        chunkDisplays[x,y,z].GetComponent.
 
  ().sharedMesh = chunksMeshes[x,lvl - y,z];
            } else {
        chunkDisplays[x,y,z].active = false;
    }
}
}
}