The summary.
DRAW CALLS AND OVERDRAW ARE WHAT USUALLY COST YOU
Combine objects sharing materials, instance repeated geometry, and limit transparent surfaces — transparency cannot be cheaply depth-sorted.
A screen-filling particle effect can halve the frame rate.
FRAGMENT SHADER COST MULTIPLIES BY PIXEL COUNT
A small addition becomes enormous at high resolution. Profile on the weakest device you support, and prepare simplified variants.
EVERY SHADOW-CASTING LIGHT RENDERS THE SCENE AGAIN
Budget them deliberately, and bake what is static.
COMPRESS EVERY TEXTURE AND AUTOMATE IMPORT SETTINGS
Uncompressed textures cost several times the memory for no visible benefit, and manual per-asset settings are forgotten.
Audit the largest textures — you will find assets far above the resolution they are ever displayed at.
INTERFACES BUILT FOR A POINTER ARE UNUSABLE WITH A CONTROLLER
Define focus movement explicitly, respect safe areas, and leave room for text that expands in translation.
ALWAYS SHIP CAMERA SENSITIVITY, INVERSION AND MOTION-REDUCTION OPTIONS
They are among the most requested accessibility settings.
