Unity

Lifecycle Order

• Awake before Start — use Awake for self-init, Start for cross-references
• OnEnable called before Start — but after Awake
• Order between scripts not guaranteed — use Script Execution Order if needed
• Awake called even if disabled — Start only when enabled

GetComponent Performance

• GetComponent every frame is slow — cache in Awake or Start
• GetComponentInChildren searches recursively — expensive on deep hierarchies
• TryGetComponent returns bool — avoids null check, slightly faster
• Use RequireComponent attribute — ensures dependency, documents requirement

Physics Timing

• Physics in FixedUpdate, not Update — consistent regardless of framerate
• FixedUpdate can run 0 or multiple times per frame — don't assume 1:1
• Rigidbody.MovePosition in FixedUpdate — transform.position bypasses physics
• Time.deltaTime in Update, Time.fixedDeltaTime in FixedUpdate — or just use deltaTime