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Fixing lag in Griffpatch platformer tutorial part 1

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PG

PlatformGamer_Pro

Posted on July 22, 2025 • Intermediate

🎮 Griffpatch platformer tutorial suddenly super laggy!

I’m following the amazing @griffpatch platformer tutorial and everything was going perfectly until I got to part 1 with the collision detection for the x-axis. 😫

Now my game is incredibly laggy - the character moves super slowly, jumping barely works half the time, and I can visually see the lag happening. It’s definitely not my computer because other projects run fine.

I think it might be something with my collision detection scripts, but I can’t figure out what’s wrong. The tutorial was working perfectly before I added that part!

Has anyone else run into this issue? I’m really stuck and would love some help debugging this! 🙏

PT

PlatformerTutor_Sam

Replied 4 hours later • ⭐ Best Answer

@PlatformGamer_Pro I know exactly what’s happening! This is a super common issue with the Griffpatch tutorial. The problem is with how you’re using the movement custom block. 🎯

🐛 The Problem: Inefficient Movement Loop

You’re probably calling the movement block like this, which creates a massive performance bottleneck:

    // WRONG - This causes lag!
Move - In Steps (speed y)

When speed y is a large negative number (like -15 when falling), Scratch tries to repeat the movement 15 times every frame. That’s what’s killing your performance!

✅ The Solution: Use Absolute Value

Here’s the fix that Griffpatch explains later in the tutorial:

    // CORRECT - This fixes the lag!
Move - In Steps ([abs v] of (speed y))

🔧 Why This Works

Here’s what’s happening behind the scenes:

flowchart TD A[Player Falls] --> B[Speed Y = -15] B --> C{Movement Method?} C -->|Wrong Way| D[Repeat 15 Times] C -->|Right Way| E[Repeat 15 Times with ABS] D --> F[15 × Collision Checks] E --> G[15 × Collision Checks] F --> H[❌ Negative Direction Confusion] G --> I[✅ Proper Direction Handling] H --> J[🐌 Lag & Glitches] I --> K[⚡ Smooth Performance] style A fill:#e1f5fe style D fill:#ffebee style E fill:#e8f5e8 style J fill:#ffcdd2 style K fill:#c8e6c9

🚀 Complete Movement System Fix

Here’s how your movement custom block should look:

    define Move - In Steps (steps)
repeat (steps)
if <(direction) = [1]> then
change x by [1]
else
change x by [-1]
end

// Check for collision after each step
if <touching [Platforms v]?> then
if <(direction) = [1]> then
change x by [-1]
else
change x by [1]
end
stop [this script v]
end
end

And call it like this:

    // For horizontal movement
if <(speed x) > [0]> then
set [direction v] to [1]
Move - In Steps ([abs v] of (speed x))
else
set [direction v] to [-1]
Move - In Steps ([abs v] of (speed x))
end

// For vertical movement  
if <(speed y) > [0]> then
set [direction v] to [1]
Move - In Steps ([abs v] of (speed y))
else
set [direction v] to [-1]
Move - In Steps ([abs v] of (speed y))
end

💡 Pro Tips for Better Performance

  • Always use absolute values for step counts in movement blocks
  • Limit collision checks - don’t check every single pixel if you don’t need to
  • Use efficient collision sprites - simple rectangles work better than complex shapes
  • Consider step size - moving 2-3 pixels per step instead of 1 can improve performance

This should completely fix your lag issue! The tutorial continues to explain this concept in more detail. Keep following along - Griffpatch’s tutorials are absolutely fantastic once you get past this common stumbling block! 🎮

PG

PlatformGamer_Pro

Replied 20 minutes later

@PlatformerTutor_Sam OH MY GOODNESS! 🤯 That was exactly it!

I changed it to use the absolute value and the lag is completely gone! My character is moving smoothly again and jumping works perfectly!

I can’t believe such a small change made such a huge difference. Thank you so much for the detailed explanation - now I understand WHY it was lagging! 🙌

Time to continue with the tutorial! 😄

GF

GriffpatchFan_Alex

Replied 1 hour later

This is such a classic mistake! 😅 I remember making the exact same error when I first followed the tutorial.

@PlatformerTutor_Sam’s explanation is spot-on. The absolute value fix is mentioned in the tutorial, but it’s easy to miss if you’re coding along quickly.

Pro tip: Always watch the entire tutorial section before coding. Griffpatch often explains the “why” after showing the “how”! 🎯

VB

Vibelf_Community

Pinned Message • Moderator

🎮 Master Platformer Development

Great problem-solving! For those working on advanced platformers, our tutors can help you with:

  • ⚡ Performance optimization techniques
  • 🎯 Advanced collision detection
  • 🏃 Smooth character movement
  • 🎨 Visual effects and polish
  • 🏆 Level design principles

📚 Related Topics

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