Understanding Smush Image Optimization's Handling of Animated GIFs and SVG Files

Many WordPress users turn to the 'Smush Image Optimization – Optimize Images | Compress & Lazy Load Images | Convert WebP & AVIF | Image CDN' plugin to improve their site's performance. However, questions often arise about how it handles specific image formats like animated GIFs and SVGs. Based on community discussions, here’s a clear explanation of what the plugin can and cannot do with these files.

The Problem with Animated GIFs and SVGs

Users frequently discover that while Smush can optimize most images, its behavior with animated GIFs and SVG files is different and can sometimes lead to unexpected results, such as broken navigation icons or confusion over resizing.

Why This Happens

The plugin is designed primarily for raster image formats (like JPG, PNG). Its core functionality is not built to process the unique structures of vector-based SVGs or the multi-frame nature of animated GIFs in the same way.

Common Solutions and Workarounds

1. For Animated GIFs

• Compression: The plugin can compress an animated GIF file without destroying its animation. The optimization process focuses on reducing file size while preserving the animation sequence.
• Resizing Limitation: A key limitation is that the automatic resize feature will not work on animated GIFs. If an animated GIF is resized, it will lose its animation. The official recommendation from the Smush team is to use a dedicated external tool (like gifgifs.com/resizer) to resize the GIF before uploading it to your WordPress site.
• Alternative Formats: For better performance, consider converting large animated GIFs to WebM or MP4 video formats. These formats are typically much smaller in file size. As long as the video is muted, you can usually enable autoplay in most modern browsers, mimicking the behavior of an animated GIF.

2. For SVG Files

• No Support: Smush does not support compression for SVG files. This is true for both the free and Pro versions of the plugin, including its CDN feature.
• Known Issue: A known behavior is that the plugin can sometimes incorrectly process an SVG file, resulting in a 1px transparent GIF being generated. This will break the display of any SVG image, such as navigation icons.
• Current Workaround: There is no setting within Smush to disable processing for specific file types. To prevent this issue, you may need to exclude pages with SVGs from optimization or seek an alternative method for serving your SVG files until the plugin's functionality is potentially updated.

Conclusion

Understanding the limitations of any optimization plugin is key to effectively managing your website. The 'Smush Image Optimization' plugin excels with standard image formats but has specific constraints with animated GIFs and SVGs. For animated GIFs, you can compress them but must resize them externally. For SVGs, the plugin currently offers no support and may cause display issues. Being aware of these details will help you plan your optimization strategy more effectively and avoid common pitfalls.