Unity Mobile 60 FPS: Draw Calls & Zero-GC Budgeting

// BAD: Allocates heap memory every single frame
void BadUpdate() {
    // 1. String concatenation generates a new string object
    scoreText.text = "Score: " + score;

    // 2. Non-cached Physics RaycastAlloc / OverlapSphereAlloc
    Collider[] hits = Physics.OverlapSphere(transform.position, 5f);

    // 3. LINQ operations allocate iterators and delegates
    var activeEnemies = enemies.Where(e => e.IsAlive).ToList();
}

// GOOD: Zero heap allocation per frame
private static readonly NonAllocArray<Collider> hitsBuffer = new(32);
private readonly StringBuilder scoreBuilder = new(32);

void GoodUpdate() {
    // 1. Reusable StringBuilder or StringFormatter
    scoreBuilder.Clear().Append("Score: ").Append(score);
    scoreText.SetText(scoreBuilder);

    // 2. NonAlloc physics queries reusing pre-allocated buffer
    int hitCount = Physics.OverlapSphereNonAlloc(transform.position, 5f, hitsBuffer.Array);

    // 3. Simple for-loops over arrays or lists
    for (int i = 0; i < enemies.Count; i++) {
        if (enemies[i].IsAlive) ProcessEnemy(enemies[i]);
    }
}