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How to fix lag issues in rock paper scissors game

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GameOptimizer_Dev

Posted on July 27, 2025 • Beginner

🎮 Rock Paper Scissors game is lagging badly

Hey everyone! I’ve been working on a rock paper scissors game but it’s running really slowly and sometimes freezes up. The game works but it’s super laggy and not fun to play.

I think the problem might be with how I’m checking for player moves and updating the display, but I’m not sure how to fix it. Any help would be amazing!

Project link: My Rock Paper Scissors Game

Thanks in advance! 🙏

PO

PerformanceOptimizer

Replied 15 minutes later • ⭐ Best Answer

Great question @GameOptimizer_Dev! Lag in Scratch games is usually caused by inefficient loops and too many checks happening every frame. Here’s how to fix your rock paper scissors game:

🔍 Common Lag Causes in Rock Paper Scissors

Here’s what typically causes performance issues:

flowchart TD A[🎮 Game Start] --> B[Player Input Detection] B --> C{Checking Method?} C -->|❌ Bad: Forever Loop| D[Continuous Checking] C -->|✅ Good: Event-Driven| E[Wait for Input] D --> F[High CPU Usage] F --> G[Game Lag] E --> H[Efficient Processing] H --> I[Smooth Gameplay] G --> J[Player Frustration] I --> K[Great User Experience] style D fill:#ffebee style F fill:#ffcdd2 style G fill:#f8bbd9 style E fill:#e8f5e8 style H fill:#c8e6c9 style I fill:#a5d6a7

🚀 Step 1: Replace Forever Loops with Events

❌ Laggy Code (Don’t do this):

    when flag clicked
forever
if <key [r v] pressed?> then
set [player choice v] to [rock]
wait [2] seconds
end
if <key [p v] pressed?> then
set [player choice v] to [paper]
wait [2] seconds
end
if <key [s v] pressed?> then
set [player choice v] to [scissors]
wait [2] seconds
end
end

✅ Optimized Code (Much better!):

    when [r v] key pressed
set [player choice v] to [rock]
broadcast [player chose v]

when [p v] key pressed
set [player choice v] to [paper]
broadcast [player chose v]

when [s v] key pressed
set [player choice v] to [scissors]
broadcast [player chose v]

🎯 Step 2: Use Broadcast Messages for Game Flow

Instead of constantly checking variables, use broadcasts to control game flow:

    when I receive [player chose v]
// Generate computer choice
set [computer choice v] to (item (pick random [1] to [3]) of [rock paper scissors v])

// Show choices
broadcast [show choices v]
wait [1] seconds

// Determine winner
broadcast [check winner v]
wait [2] seconds

// Reset for next round
broadcast [new round v]

🎨 Step 3: Optimize Visual Updates

For showing/hiding costumes efficiently:

    when I receive [show choices v]
// Player sprite
if <(player choice) = [rock]> then
switch costume to [rock v]
else
if <(player choice) = [paper]> then
switch costume to [paper v]
else
switch costume to [scissors v]
end
end
show

// Computer sprite  
if <(computer choice) = [rock]> then
switch costume to [rock v]
else
if <(computer choice) = [paper]> then
switch costume to [paper v]
else
switch costume to [scissors v]
end
end
show

🏆 Step 4: Efficient Winner Detection

Clean logic for determining the winner:

    when I receive [check winner v]
if <(player choice) = (computer choice)> then
set [result v] to [It's a tie!]
else
if <<(player choice) = [rock]> and <(computer choice) = [scissors]>> then
set [result v] to [You win!]
else
if <<(player choice) = [paper]> and <(computer choice) = [rock]>> then
set [result v] to [You win!]
else
if <<(player choice) = [scissors]> and <(computer choice) = [paper]>> then
set [result v] to [You win!]
else
set [result v] to [Computer wins!]
end
end
end
end

// Show result
say (result) for [2] seconds

🔄 Step 5: Clean Reset System

Proper cleanup between rounds:

    when I receive [new round v]
// Hide choice sprites
hide

// Clear variables
set [player choice v] to []
set [computer choice v] to []
set [result v] to []

// Show instructions
say [Press R for Rock, P for Paper, S for Scissors] for [3] seconds

⚡ Step 6: Additional Performance Tips

Here are some extra optimizations:

Avoid Unnecessary Waits:

    // ❌ Don't do this
forever
wait [0.1] seconds
// check something
end

// ✅ Do this instead
when I receive [something happened v]
// respond immediately

Use Custom Blocks for Repeated Code:

    define show choice (choice)
if <(choice) = [rock]> then
switch costume to [rock v]
else
if <(choice) = [paper]> then
switch costume to [paper v]
else
switch costume to [scissors v]
end
end
show

Limit Visual Effects:

    // Keep effects simple for better performance
when I receive [player wins v]
repeat [3]
change [color v] effect by [25]
wait [0.1] seconds
end
clear graphic effects

These changes should make your game run much smoother! The key is to avoid continuous checking and use event-driven programming instead. Good luck! 🎮✨

GO

GameOptimizer_Dev

Replied 30 minutes later

@PerformanceOptimizer This is incredible! Thank you so much! 🎉

I replaced all my forever loops with broadcast messages and the game is running perfectly now. The difference is night and day! I had no idea that forever loops could cause so much lag.

One quick question - should I avoid using forever loops completely, or are there times when they’re okay to use?

PO

PerformanceOptimizer

Replied 1 hour later

@GameOptimizer_Dev Great question! Forever loops aren’t always bad - they’re perfect for:

  • 🎵 Background music loops
  • 🌟 Continuous animations (like rotating stars)
  • 🎮 Game physics (like gravity)
  • ⏰ Timers and countdowns

The key is to always include a wait block in forever loops to prevent lag. Even wait 0.01 seconds makes a huge difference!

VB

Vibelf_Community

Pinned Message • Moderator

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  • ⚡ Advanced performance techniques
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