docs: add benchmark page and performance references

Author: cshum

docs/docs/benchmarks.mdx

@@ -90,11 +90,6 @@ xychart-beta
   </div>
 </div>
 
-- JPEG: imgproxy leads in this setup
-- PNG: imagor leads
-- WebP: imgproxy leads in this setup
-- AVIF: imagor is slightly ahead of imgproxy in this setup
-
 Benchmark shape:
 
 - AWS EC2 `c7i.large`
@@ -120,4 +115,4 @@ The exact ranking still depends on image format, output settings, source shape,
 
 - imagor and imgproxy are both libvips-based, so the gap is often determined by request-path overhead, source handling, and encoder settings rather than by the core image library alone
 - thumbor remains a strong compatibility reference, but its Pillow-based pipeline is generally slower on this workload
-- for AVIF, encoder settings matter a lot; benchmark conclusions should always be read together with the exact runtime configuration
+- for AVIF, encoder settings matter a lot; benchmark conclusions should always be read together with the exact runtime configuration