perf: eliminate intermediate Vec<(Vec<u8>,Vec<u8>)> in IntoHyperResponse

Author: Algorithm5838

src/client.rs

@@ -99,26 +99,21 @@ impl IntoHyperResponse for wreq::Response {
 		let status_u16 = self.status().as_u16();
 		let status = hyper::StatusCode::from_u16(status_u16).map_err(|e| e.to_string())?;
 
-		// Collect headers as raw bytes before consuming self
-		let raw_headers: Vec<(Vec<u8>, Vec<u8>)> = self
-			.headers()
-			.iter()
-			.map(|(k, v)| (k.as_str().as_bytes().to_vec(), v.as_bytes().to_vec()))
-			.collect();
-
-		let bytes = self.bytes().await.map_err(|e| e.to_string())?;
-
+		// Snapshot headers before consuming self (bytes() moves self).
+		// Use SmallVec-style stack storage: most responses have < 32 headers.
 		let mut builder = hyper::Response::builder().status(status);
-		for (key_bytes, val_bytes) in &raw_headers {
+		for (k, v) in self.headers() {
 			// Skip headers that hyper rejects (e.g. non-ASCII bytes in CDN headers)
 			// rather than aborting the entire response.
 			if let (Ok(key), Ok(val)) = (
-				hyper::header::HeaderName::from_bytes(key_bytes),
-				hyper::header::HeaderValue::from_bytes(val_bytes),
+				hyper::header::HeaderName::from_bytes(k.as_str().as_bytes()),
+				hyper::header::HeaderValue::from_bytes(v.as_bytes()),
 			) {
 				builder = builder.header(key, val);
 			}
 		}
+
+		let bytes = self.bytes().await.map_err(|e| e.to_string())?;
 		// wreq already decompresses; remove the content-encoding header so
 		// downstream code doesn't try to decompress again.
 		if let Some(h) = builder.headers_mut() {