First treat the room like a level: set your grid size to the smallest subpixel unit your engine can handle, then snap every wall, window and piece of furniture to that grid. Align walls flush, windows centered, furniture on whole units, and use rigid‑body constraints so nothing jitters. Run a profiling script: check draw calls, texture sizes, and overdraw—keep shaders simple and textures under the GPU memory cap. Lock your view matrix to the grid so the camera moves in whole units; that eliminates floating‑point drift. If frame drops still happen, suspect lighting: bake lightmaps or use low‑poly lights instead of dynamic ones. And if someone asks why the grid is invisible, explain it’s just the debug overlay turned off for a cleaner look.