Benchmark: AVIF Achieves 91% Compression in WordPress Image Optimization Test

JPEG vs WebP vs AVIF in WordPress: Real Benchmark Data (4 Plugins Tested)

A benchmark of four major WordPress image optimization plugins—ShortPixel, Imagify, Optimole, and EWWW—was conducted on a standardized server environment. The test utilized a 2400×1590px source image to measure real-world lossy compression efficiency across modern formats.

Why This Matters

While marketing materials often claim parity between optimization tools, actual performance varies significantly based on the compression algorithms and format support. This test highlights that choosing the right plugin and format, specifically AVIF, can reduce a 494 KB image to just 43 KB, a critical gain for Core Web Vitals and mobile performance.

Key Insights

• AVIF outperformed JPEG by a margin of 9%, reducing a 494 KB source to 43 KB via ShortPixel (2026).
• ShortPixel achieved the highest lossy compression across all formats, including an 82% reduction for standard JPEG files.
• Format support disparity exists where tools like EWWW Image Optimizer lock AVIF behind paid tiers, whereas others provide it natively.
• Optimole’s CDN-based approach resulted in significantly larger AVIF files (133 KB) compared to ShortPixel’s local processing (43 KB).
• WebP remains a strong middle ground, consistently offering 81-88% reduction across all tested plugins.

Practical Applications

• Use Case: Implementing ShortPixel for high-traffic sites to achieve 91.3% compression on high-resolution photography. Pitfall: Using plugins that label settings as ‘aggressive’ without verifying actual byte-count reductions.
• Use Case: Automating format switching per browser to ensure AVIF is served to compatible clients. Pitfall: Manually configuring format delivery which increases maintenance overhead and potential for broken images.

References:

• https://dev.to/biancarus/jpeg-vs-webp-vs-avif-in-wordpress-real-benchmark-data-4-plugins-tested-j83