On product-heavy stores, images are 60–80% of page weight — which makes the optimization plugin the highest-leverage performance purchase after caching. We took one 500-image WooCommerce library (unoptimized camera JPEGs and PNGs) and processed it through ShortPixel, Imagify, and Smush, comparing what came out the other side.
The size results
Same 500 images, each plugin’s recommended settings (WebP generation on):
| Plugin | Total size after | Reduction | AVIF | Bulk time |
|---|---|---|---|---|
| ShortPixel | 78 MB (from 212 MB) | 63% | Yes | 41 min |
| Imagify | 84 MB | 60% | Yes | 47 min |
| Smush Pro | 89 MB | 58% | Yes (CDN route) | 52 min |
All three compress well. ShortPixel’s aggressive mode edged ahead; Smush leaned on its CDN delivery model rather than local files. Differences at this scale: ~11 MB total — real, but small next to CSS budgets on badly built themes.
Where they genuinely differ
- Pricing model. ShortPixel credits per image (re-optimization costs credits unless careful); Imagify per-MB monthly; Smush Pro per-membership (includes the CDN). Heavy libraries with frequent uploads: Imagify’s model is friendlier. One-off bulk conversions: ShortPixel’s quality wins.
- WebP delivery mechanics. ShortPixel serves WebP via rewrite or <picture> tags; Imagify via rewrite with .htaccess rules that occasionally fight security plugins. Smush routes through their CDN by default — fine until the CDN is the bottleneck for EU traffic.
- Retina/AVIF handling. All three now do AVIF; ShortPixel’s AVIF output was consistently smaller in our sample (a 4–8% edge).
The free option reality check
Smush’s free tier (no CDN, no AVIF, 5MB limit per image) handled our library at 94 MB — respectable. For a small site it is enough; for a store where LCP pays the bills, the paid tiers earn their cost, as the numbers in the CWV guide suggest — hero images dominated most of our slow-LCP findings.
Our setup notes
- Exclude LCP images from lazy-loading (every one of these plugins lazy-loads by default; it hurts LCP above the fold — same trap as our WP Rocket review).
- Convert before upload when you can: our own pipeline uses
cwebp -q 82and skips plugins entirely for new uploads — the script-level audit still catches leftover old files.
ShortPixel's aggressive mode produced the smallest files in our test — 63% reduction across 500 images, and the smallest AVIF output. Imagify was within 3%. Depends on usage: one-time bulk conversions favor ShortPixel credits; ongoing uploads favor Imagify's per-MB monthly plan. At large libraries the pricing models diverge sharply. For small sites, yes — free Smush got our library 56% smaller. Stores chasing LCP targets benefit from AVIF and better delivery mechanics in paid tiers. When applied to the LCP image, yes — it delays the largest visible element. Exclude above-the-fold images from lazy loading in every optimizer plugin's settings.Which image optimizer compresses best?
Is ShortPixel or Imagify cheaper?
Can I use free Smush instead of paid optimizers?
Does lazy loading hurt LCP?
