Obstacle avoidance in Unity - Performance & Optimization

Performance: Obstacle avoidance

MEDIUM IMPACT

This affects the frame rate and responsiveness of the game by how often and how complex the obstacle detection and avoidance calculations are.

Detecting and avoiding obstacles for a moving character in a game scene

Unity

void Update() {
  if (Time.frameCount % 5 == 0) {
    RaycastHit hit;
    if (Physics.Raycast(transform.position, transform.forward, out hit, 10f)) {
      if (hit.collider.CompareTag("Obstacle")) {
        transform.Rotate(0, 90, 0);
      }
    }
  }
  transform.Translate(Vector3.forward * Time.deltaTime * speed);
}

Limits raycast checks to every 5 frames, reducing physics calls and smoothing CPU usage.

📈 Performance Gainreduces physics raycasts by 80%, lowering CPU load and improving frame rate stability

Detecting and avoiding obstacles for a moving character in a game scene

Unity

void Update() {
  RaycastHit hit;
  if (Physics.Raycast(transform.position, transform.forward, out hit, 10f)) {
    if (hit.collider.CompareTag("Obstacle")) {
      transform.Rotate(0, 90, 0);
    }
  }
  transform.Translate(Vector3.forward * Time.deltaTime * speed);
}

This runs a raycast every frame without any optimization, causing many physics checks and potential frame drops.

📉 Performance Costtriggers 1 physics raycast per frame, causing CPU spikes especially with many moving objects

Performance Comparison

Pattern	Physics Calls	CPU Usage	Frame Drops	Verdict
Raycast every frame	High (1 per frame)	High	Frequent	[X] Bad
Raycast every 5 frames	Low (1 per 5 frames)	Low	Rare	[OK] Good

Rendering Pipeline

Obstacle avoidance calculations run on the CPU and affect the game loop update cycle. Frequent physics raycasts increase CPU usage and can delay frame rendering.

→Game Loop Update

→Physics Calculation

⚠️ BottleneckPhysics Calculation stage due to frequent raycasts

Optimization Tips

1Avoid running physics raycasts every frame if possible.

2Use simpler colliders and limit raycast targets to reduce cost.

3Batch or space out obstacle detection checks to smooth CPU usage.

Performance Quiz - 3 Questions

What is the main performance cost of running obstacle avoidance with raycasts every frame?

A High CPU usage due to frequent physics raycasts

B Increased GPU load from rendering

C More memory usage from storing raycast results

D Longer loading times at game start

DevTools: Unity Profiler

How to check: Open Unity Profiler, run the game, and look at CPU Usage and Physics sections to see how many raycasts are called per frame.

What to look for: High spikes in Physics raycast calls indicate inefficient obstacle avoidance; smoother CPU usage means better performance.