How to optimize SVG to improve performance

SVG optimization is crucial for improving web page performance and user experience. Here are common SVG optimization techniques:

1. Remove Unnecessary Code

• Delete metadata added by editors (like <title>Created with...</title>)
• Remove comments and blank lines
• Delete unused definitions and styles
• Use tools like SVGO for automatic optimization

2. Simplify Paths

• Use shorter path commands (like h instead of H)
• Merge adjacent identical commands
• Reduce decimal precision (e.g., 50.123456 to 50.12)
• Use relative coordinates instead of absolute coordinates

3. Optimize Attributes

• Remove default value attributes (e.g., fill="black" can be omitted)
• Use shorthand attributes (e.g., stroke instead of stroke-color)
• Merge identical styles into class or <style> tags

4. Compress SVG Files

• Use gzip compression (server configuration)
• Optimize with tools like SVGO
• Remove DOCTYPE declaration (doesn't affect rendering)

5. Use SVG Sprite

• Merge multiple icons into one SVG file
• Use <symbol> and <use> elements to reuse graphics
• Reduce HTTP requests

Example:

svg
<svg style="display: none;">
  <symbol id="icon-home" viewBox="0 0 24 24">
    <path d="M10 20v-6h4v6h5v-8h3L12 3 2 12h3v8z"/>
  </symbol>
  <symbol id="icon-user" viewBox="0 0 24 24">
    <path d="M12 12c2.21 0 4-1.79 4-4s-1.79-4-4-4-4 1.79-4 4 1.79 4 4 4zm0 2c-2.67 0-8 1.34-8 4v2h16v-2c0-2.66-5.33-4-8-4z"/>
  </symbol>
</svg>

<!-- Use icons -->
<svg><use href="#icon-home"/></svg>
<svg><use href="#icon-user"/></svg>

6. Inline Critical SVGs

• Inline critical SVGs for first-screen rendering into HTML
• Avoid additional HTTP requests
• Non-critical SVGs can be lazy-loaded

7. Use viewBox Instead of width/height

• Use viewBox for responsive scaling
• Control display size via CSS
• Improve flexibility

8. Reduce Element Count

• Merge paths that can be merged
• Use <g> for grouping instead of multiple independent elements
• Avoid unnecessary nesting

9. Optimize Animation Performance

• Prioritize CSS animations (GPU accelerated)
• Use transform and opacity properties
• Avoid animating width, height, left, top properties

10. Recommended Tools

• SVGO: Powerful SVG optimization tool
• SVGOMG: Online SVG optimization tool
• Iconfont: Icon font and SVG management
• Figma/Sketch: Optimize SVG when exporting

Optimization Example:

bash
# Optimize with SVGO
npx svgo input.svg -o output.svg

# Batch optimize
npx svgo -f ./icons -o ./optimized

Performance Testing:

• Use Lighthouse to test page performance
• Check SVG file size and load time
• Monitor rendering performance