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Ghostty is built for speed. It uses GPU acceleration for rendering, dedicated IO threading, and careful optimizations to deliver one of the fastest terminal emulator experiences available.

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Performance Highlights

GPU Acceleration

Metal on macOS, OpenGL on Linux for hardware-accelerated rendering

Dedicated IO Thread

Low-jitter IO processing for smooth heavy output

Ligature Support

Metal renderer supports ligatures at 60fps - the only terminal with this capability on macOS

Competitive Speed

2-4x faster than iTerm and Kitty for large file operations

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Rendering Architecture

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Multi-Renderer Design

Ghostty uses different rendering backends optimized for each platform:
Metal renderer provides native GPU acceleration:
  • Direct Metal API usage (no OpenGL compatibility layer)
  • Full ligature support at 60fps+
  • CoreText font integration
  • Maintains ~60fps under heavy load
Ghostty is one of only two terminal emulators using Metal directly, and the only one supporting ligatures with Metal rendering.

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Frame Rate Management

Ghostty intelligently manages frame rates:
  • Heavy load: Maintains ~60fps
  • Idle: Renders only on change (power efficient)
  • Animation: Smooth cursor blink and visual effects

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IO Performance

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Dedicated IO Thread

Ghostty uses a separate thread for IO operations: 
Main Thread          IO Thread
    |                    |
    |  ← Terminal data ← |
    ↓                    ↓
 Render            Read from PTY
Benefits:
  • Very little jitter under heavy IO load
  • Non-blocking rendering
  • Smooth experience with cat large-file.txt

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Benchmark Results

From the README:
For IO, we have a dedicated IO thread that maintains very little jitter under heavy IO load (i.e. cat <big file>.txt). On benchmarks for IO, we’re usually within a small margin of other fast terminal emulators.
Comparative performance (reading plain text dumps):
  • 4x faster than iTerm
  • 4x faster than Kitty
  • 2x faster than Terminal.app
  • Similar speed to Alacritty (give or take)
Ghostty provides similar performance to Alacritty while offering significantly more features.

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Optimization Tips

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Font Rendering

1

Choose monospace fonts

Monospace fonts render faster than proportional fonts:
font-family = "JetBrains Mono"
font-size = 13
2

Disable unnecessary features

Disable ligatures if you don’t need them:
font-feature = -calt,-liga,-dlig
3

Adjust font metrics conservatively

Excessive adjustments can impact rendering:
# Minimal adjustments for performance
adjust-cell-height = 0
adjust-cell-width = 0

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Background and Effects

# Disable transparency
background-opacity = 1.0

# No background image
# background-image = (not set)

# No blur
# background-blur = (not set)
Background images are duplicated in VRAM per-terminal, which can increase memory usage for large images.

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Alpha Blending

Choose the right alpha blending mode: 
# Native color space (macOS default)
alpha-blending = native

# Linear gamma correction (Linux default, good balance)
alpha-blending = linear-corrected

# Pure linear blending
alpha-blending = linear
linear-corrected provides the best balance of accuracy and performance.

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Resource Usage

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Memory Management

Ghostty is efficient with memory:
  • Scrollback limit: Configure to match your needs 
    scrollback-limit = 10000  # Default
  • Image storage: Limit memory for image protocols 
    image-storage-limit = 320000000  # 320MB default

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GPU Memory (VRAM)

Factors affecting VRAM usage:
  1. Font atlas: Cached glyphs (automatically managed)
  2. Background images: Duplicated per-terminal (see warning above)
  3. Image protocol: Controlled by image-storage-limit

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Benchmarking

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Test IO Performance

# Generate a large text file
seq 1 100000 > numbers.txt

# Time rendering
time cat numbers.txt

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Test Rendering Performance

# Stress test with continuous output
yes | head -n 1000000

# Watch CPU usage
top -pid $(pgrep ghostty)

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Scrollback Performance

# Fill scrollback buffer
seq 1 100000

# Test scrollback speed
# Use Page Up/Down or scrollbar

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Performance Comparison

FeatureGhosttyAlacrittyKittyiTerm2Terminal.app
GPU Acceleration✅ Metal/OpenGL✅ OpenGL✅ OpenGL✅ Metal (no ligatures)❌ CPU
Ligatures (macOS)✅ 60fps❌✅❌ (CPU fallback)✅
IO Thread✅✅✅✅❌
Large File SpeedVery FastVery FastFastSlowMedium
Memory UsageLowVery LowMediumHighLow

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Future Improvements

From the README:
Despite being very fast, there is a lot of room for improvement here.
Planned optimizations:
  • Better benchmarking suite
  • Additional rendering optimizations
  • Shared texture memory for background images
  • Per-window background images

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Configuration Examples

# Optimized for speed
font-family = "JetBrains Mono"
font-size = 12
font-feature = -calt,-liga  # Disable ligatures

background-opacity = 1.0
alpha-blending = native

scrollback-limit = 5000
image-storage-limit = 100000000

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Monitoring Performance

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macOS Activity Monitor

  1. Open Activity Monitor
  2. Find “Ghostty” process
  3. Monitor:
    • CPU%: Should be low when idle
    • Memory: Depends on scrollback and images
    • GPU: Check “Window Server” for GPU usage

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Linux Tools

# CPU and memory
top -p $(pgrep ghostty)

# Detailed stats
htop -p $(pgrep ghostty)

# GPU usage (NVIDIA)
nvidia-smi

# GPU usage (Intel/AMD)
intel_gpu_top
# or
radeontop

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Key Takeaways

GPU Accelerated

Metal on macOS, OpenGL on Linux for maximum rendering speed

Competitive Speed

2-4x faster than many alternatives for IO operations

Low Resource Usage

Efficient memory management with configurable limits

Room to Grow

Already very fast, with optimizations planned