Compression & media
Per-domain rule
integer · seconds
webp_transformation_min_age
Minimum cache age before an image is re-encoded to WebP.
- Config key
webp_transformation_min_age- Scope
- Per-domain rule
- Type
- integer · seconds
- Default
21600
How long a cached image must have lived before the proxy spends CPU converting it to WebP. The default is 21600 seconds (6 hours), which avoids transforming images that are about to be invalidated anyway.
⚡Tuning
Lower it for galleries of long-lived images so the WebP win lands sooner; raise it if your images churn rapidly and conversions would be wasted.
webp_transformation_min_age = 21600