diff --git a/crates/clawhdf5-format/src/object_header.rs b/crates/clawhdf5-format/src/object_header.rs
index afcb9c5..2045a4c 100644
--- a/crates/clawhdf5-format/src/object_header.rs
+++ b/crates/clawhdf5-format/src/object_header.rs
@@ -295,7 +295,13 @@ impl ObjectHeader {
     /// The messages of one version-1 chunk: each checked and appended to
     /// `messages` (NIL ones dropped), each continuation added to `spans`.
     /// Returns how many messages (NIL ones included) the chunk holds.
-    #[inline(never)]
+    ///
+    /// Inlined into the chunk loop: kept out of line (`#[inline(never)]`,
+    /// 4313917), the call cost `ObjectHeader::parse` about 2.5 ns per
+    /// header, 4% on small version-1 headers (A/B builds, 2026-09-27; see
+    /// `BENCHMARKS.md`). Without an attribute the compiler keeps it out of
+    /// line too.
+    #[inline]
     fn parse_v1_messages(
         data: &[u8],
         offset_size: u8,