diff --git a/include/bitcoin/system/hash/sha/algorithm.hpp b/include/bitcoin/system/hash/sha/algorithm.hpp
index 480d470de4..e5e635a4a6 100644
--- a/include/bitcoin/system/hash/sha/algorithm.hpp
+++ b/include/bitcoin/system/hash/sha/algorithm.hpp
@@ -234,8 +234,8 @@ class algorithm
     INLINE static constexpr void input(buffer_t& buffer, const block_t& block) NOEXCEPT;
     INLINE static constexpr void input_left(auto& buffer, const half_t& half) NOEXCEPT;
     INLINE static constexpr void input_right(auto& buffer, const half_t& half) NOEXCEPT;
-    INLINE static constexpr void reinput_left(auto& buffer, const auto& left) NOEXCEPT;
-    INLINE static constexpr void reinput_right(auto& buffer, const auto& right) NOEXCEPT;
+    INLINE static constexpr void inject_left(auto& buffer, const auto& left) NOEXCEPT;
+    INLINE static constexpr void inject_right(auto& buffer, const auto& right) NOEXCEPT;
     INLINE static constexpr digest_t output(const state_t& state) NOEXCEPT;
 
     /// Padding.
diff --git a/include/bitcoin/system/impl/hash/sha/algorithm_double.ipp b/include/bitcoin/system/impl/hash/sha/algorithm_double.ipp
index ea13a311ae..0ccd6c2361 100644
--- a/include/bitcoin/system/impl/hash/sha/algorithm_double.ipp
+++ b/include/bitcoin/system/impl/hash/sha/algorithm_double.ipp
@@ -84,7 +84,7 @@ double_hash(const block_t& block) NOEXCEPT
 {
     static_assert(is_same_type<state_t, chunk_t>);
 
-    const auto hash2 = [](const block_t& block) NOEXCEPT
+    const auto hasher = [](const block_t& block) NOEXCEPT
     {
         auto state = H::get;
         buffer_t buffer{};
@@ -95,7 +95,7 @@ double_hash(const block_t& block) NOEXCEPT
         compress(state, buffer);
 
         // Second hash
-        reinput_left(buffer, state);
+        inject_left(buffer, state);
         pad_half(buffer);
         schedule(buffer);
         state = H::get;
@@ -106,7 +106,7 @@ double_hash(const block_t& block) NOEXCEPT
 
     if (std::is_constant_evaluated())
     {
-        return hash2(block);
+        return hasher(block);
     }
     else if constexpr (native && SHA::strength == 256)
     {
@@ -114,7 +114,7 @@ double_hash(const block_t& block) NOEXCEPT
     }
     else
     {
-        return hash2(block);
+        return hasher(block);
     }
 }
 
@@ -124,7 +124,7 @@ double_hash(const half_t& half) NOEXCEPT
 {
     static_assert(is_same_type<state_t, chunk_t>);
 
-    const auto hash2 = [](const half_t& half) NOEXCEPT
+    const auto hasher = [](const half_t& half) NOEXCEPT
     {
         auto state = H::get;
         buffer_t buffer{};
@@ -134,7 +134,7 @@ double_hash(const half_t& half) NOEXCEPT
         compress(state, buffer);
 
         // Second hash
-        reinput_left(buffer, state);
+        inject_left(buffer, state);
         pad_half(buffer);
         schedule(buffer);
         state = H::get;
@@ -145,7 +145,7 @@ double_hash(const half_t& half) NOEXCEPT
 
     if (std::is_constant_evaluated())
     {
-        return hash2(half);
+        return hasher(half);
     }
     else if constexpr (native && SHA::strength == 256)
     {
@@ -153,7 +153,7 @@ double_hash(const half_t& half) NOEXCEPT
     }
     else
     {
-        return hash2(half);
+        return hasher(half);
     }
 }
 
@@ -163,7 +163,7 @@ double_hash(const half_t& left, const half_t& right) NOEXCEPT
 {
     static_assert(is_same_type<state_t, chunk_t>);
 
-    const auto hash2 = [](const half_t& left, const half_t& right) NOEXCEPT
+    const auto hasher = [](const half_t& left, const half_t& right) NOEXCEPT
     {
         auto state = H::get;
         buffer_t buffer{};
@@ -175,7 +175,7 @@ double_hash(const half_t& left, const half_t& right) NOEXCEPT
         compress(state, buffer);
 
         // Second hash
-        reinput_left(buffer, state);
+        inject_left(buffer, state);
         pad_half(buffer);
         schedule(buffer);
         state = H::get;
@@ -186,7 +186,7 @@ double_hash(const half_t& left, const half_t& right) NOEXCEPT
 
     if (std::is_constant_evaluated())
     {
-        return hash2(left, right);
+        return hasher(left, right);
     }
     else if constexpr (native && SHA::strength == 256)
     {
@@ -194,7 +194,7 @@ double_hash(const half_t& left, const half_t& right) NOEXCEPT
     }
     else
     {
-        return hash2(left, right);
+        return hasher(left, right);
     }
 }
 
diff --git a/include/bitcoin/system/impl/hash/sha/algorithm_functions.ipp b/include/bitcoin/system/impl/hash/sha/algorithm_functions.ipp
index 4cfb1e2df1..98b6d6d13a 100644
--- a/include/bitcoin/system/impl/hash/sha/algorithm_functions.ipp
+++ b/include/bitcoin/system/impl/hash/sha/algorithm_functions.ipp
@@ -16,8 +16,8 @@
  * You should have received a copy of the GNU Affero General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-#ifndef LIBBITCOIN_SYSTEM_HASH_SHA_ALGORITHM_FUCNTIONS_IPP
-#define LIBBITCOIN_SYSTEM_HASH_SHA_ALGORITHM_FUCNTIONS_IPP
+#ifndef LIBBITCOIN_SYSTEM_HASH_SHA_ALGORITHM_FUNCTIONS_IPP
+#define LIBBITCOIN_SYSTEM_HASH_SHA_ALGORITHM_FUNCTIONS_IPP
 
 // 4.1 Functions
 // ============================================================================
diff --git a/include/bitcoin/system/impl/hash/sha/algorithm_konstant.ipp b/include/bitcoin/system/impl/hash/sha/algorithm_konstant.ipp
index 26cf225d14..99d47edd0a 100644
--- a/include/bitcoin/system/impl/hash/sha/algorithm_konstant.ipp
+++ b/include/bitcoin/system/impl/hash/sha/algorithm_konstant.ipp
@@ -252,15 +252,16 @@ TEMPLATE
 INLINE constexpr void CLASS::
 konstant(buffer_t& buffer) NOEXCEPT
 {
-    if (std::is_constant_evaluated())
-    {
-        konstant_(buffer);
-    }
-    else if constexpr (vector && !with_clang)
-    {
-        vector_konstant(buffer);
-    }
-    else
+    // This optimization is neutral in 4/8/16 lane sha256 perf.
+    ////if (std::is_constant_evaluated())
+    ////{
+    ////    konstant_(buffer);
+    ////}
+    ////else if constexpr (vector && !with_clang)
+    ////{
+    ////    vector_konstant(buffer);
+    ////}
+    ////else
     {
         konstant_(buffer);
     }
diff --git a/include/bitcoin/system/impl/hash/sha/algorithm_merkle.ipp b/include/bitcoin/system/impl/hash/sha/algorithm_merkle.ipp
index 05d8ae2a56..aa3d8e4f98 100644
--- a/include/bitcoin/system/impl/hash/sha/algorithm_merkle.ipp
+++ b/include/bitcoin/system/impl/hash/sha/algorithm_merkle.ipp
@@ -372,7 +372,7 @@ merkle_hash_vector(idigests_t& digests, iblocks_t& blocks) NOEXCEPT
                 compress_(xstate, xbuffer);
 
                 // Second hash
-                reinput_left(xbuffer, xstate);
+                inject_left(xbuffer, xstate);
                 pad_half(xbuffer);
                 schedule_(xbuffer);
                 xstate = initial;
diff --git a/include/bitcoin/system/impl/hash/sha/algorithm_native.ipp b/include/bitcoin/system/impl/hash/sha/algorithm_native.ipp
index b63156804e..f605fa9a80 100644
--- a/include/bitcoin/system/impl/hash/sha/algorithm_native.ipp
+++ b/include/bitcoin/system/impl/hash/sha/algorithm_native.ipp
@@ -21,8 +21,10 @@
 
 // Native (SHA-NI or NEON)
 // ============================================================================
-// The iterative method is used for sha native as it is an order of magnitude
-// more efficient and cannot benefit from vectorization.
+// The rotating variables method is used for sha native. Tha native
+// instructions rely on register locality to achieve performance benefits.
+// Implementation of native sha using buffer expansion is horribly slow.
+// This split creates bifurcations (additional complexities) in this template.
 
 namespace libbitcoin {
 namespace system {
@@ -98,9 +100,6 @@ round_4(xint128_t& state0, xint128_t& state1, xint128_t message) NOEXCEPT
 
 // Platform agnostic.
 // ----------------------------------------------------------------------------
-// Individual state vars are used vs. array to ensure register persistence.
-// This creates bifurcations in this template because of the lack of a buffer
-// and the differing optimal locations for applying endianness conversions.
 
 TEMPLATE
 template <bool Swap>
@@ -223,6 +222,9 @@ native_transform(state_t& state, const auto& block) NOEXCEPT
 // accumulation and performs big-endian conversion from state_t to digest_t.
 // As padding blocks are generated and therefore do not require endianness
 // conversion, those calls are not applied when transforming the pad block.
+// This lack of conversion also applies to double hashing. In both cases
+// the "inject" functions are using in place of the "input" functions.
+// There is no benefit to caching pading because it is not prescheduled.
 // ----------------------------------------------------------------------------
 
 TEMPLATE
@@ -251,8 +253,6 @@ template <size_t Blocks>
 typename CLASS::digest_t CLASS::
 native_finalize(state_t& state) NOEXCEPT
 {
-    // We could use Blocks to cache padding but given the padding blocks are
-    // unscheduled when performing native transformations there's no benefit.
     return native_finalize(state, Blocks);
 }
 
@@ -273,7 +273,7 @@ native_finalize_second(const state_t& state) NOEXCEPT
     // Hash a state value and finalize it.
     auto state2 = H::get;
     words_t block{};
-    reinput_left(block, state);             // swapped
+    inject_left(block, state);              // swapped
     pad_half(block);                        // swapped
     return native_finalize(state2, block);  // no block swap (swaps state)
 }
@@ -288,7 +288,7 @@ native_finalize_double(state_t& state, size_t blocks) NOEXCEPT
 
     // This is native_finalize_second() but reuses the initial block.
     auto state2 = H::get;
-    reinput_left(block, state);             // swapped
+    inject_left(block, state);              // swapped
     pad_half(block);                        // swapped
     return native_finalize(state2, block);  // no block swap (swaps state)
 }
@@ -316,8 +316,8 @@ native_hash(const half_t& left, const half_t& right) NOEXCEPT
 {
     auto state = H::get;
     words_t block{};
-    reinput_left(block, array_cast<word_t>(left));      // unswapped
-    reinput_right(block, array_cast<word_t>(right));    // unswapped
+    inject_left(block, array_cast<word_t>(left));   // unswapped
+    inject_right(block, array_cast<word_t>(right)); // unswapped
     native_transform<true>(state, block);   // swap
     return native_finalize<one>(state);     // no block swap (swaps state)
 }
@@ -335,7 +335,7 @@ native_double_hash(const block_t& block) NOEXCEPT
 
     // Second hash
     words_t block2{};
-    reinput_left(block2, state);            // swapped
+    inject_left(block2, state);             // swapped
     pad_half(block2);                       // swapped
     state = H::get;                         // [reuse state var]
     return native_finalize(state, block2);  // no block swap (swaps state)
@@ -352,7 +352,7 @@ native_double_hash(const half_t& half) NOEXCEPT
     native_transform<false>(state, block);  // no block swap
 
     // Second hash
-    reinput_left(block, state);             // swapped
+    inject_left(block, state);              // swapped
     pad_half(block);                        // swapped
     state = H::get;                         // [reuse state var]
     return native_finalize(state, block);   // no block swap (swaps state)
@@ -364,13 +364,13 @@ native_double_hash(const half_t& left, const half_t& right) NOEXCEPT
 {
     auto state = H::get;
     words_t block{};
-    reinput_left(block, array_cast<word_t>(left));      // unswapped
-    reinput_right(block, array_cast<word_t>(right));    // unswapped
-    native_transform<true>(state, block);               // swap
-    native_transform<false>(state, pad_block());        // swapped
+    inject_left(block, array_cast<word_t>(left));   // unswapped
+    inject_right(block, array_cast<word_t>(right)); // unswapped
+    native_transform<true>(state, block);           // swap
+    native_transform<false>(state, pad_block());    // swapped
 
     // Second hash
-    reinput_left(block, state);             // swapped
+    inject_left(block, state);              // swapped
     pad_half(block);                        // swapped
     state = H::get;                         // [reuse state var]
     return native_finalize(state, block);   // no block swap (swaps state)
diff --git a/include/bitcoin/system/impl/hash/sha/algorithm_parsing.ipp b/include/bitcoin/system/impl/hash/sha/algorithm_parsing.ipp
index 9ba22b5f38..c612254af2 100644
--- a/include/bitcoin/system/impl/hash/sha/algorithm_parsing.ipp
+++ b/include/bitcoin/system/impl/hash/sha/algorithm_parsing.ipp
@@ -58,6 +58,7 @@ input(buffer_t& buffer, const block_t& block) NOEXCEPT
     }
     else if constexpr (bc::is_little_endian)
     {
+        // This optimization is neutral in 4/8/16 lane sha256 perf.
         ////if constexpr (have_lanes<word_t, 16> && !with_clang)
         ////{
         ////    using xword_t = to_extended<word_t, 16>;
@@ -131,6 +132,7 @@ input_left(auto& buffer, const half_t& half) NOEXCEPT
     }
     else if constexpr (bc::is_little_endian)
     {
+        // This optimization is neutral in 4/8 lane sha256 perf.
         ////if constexpr (have_lanes<word_t, 8> && !with_clang)
         ////{
         ////    using xword_t = to_extended<word_t, 8>;
@@ -185,6 +187,7 @@ input_right(auto& buffer, const half_t& half) NOEXCEPT
     }
     else if constexpr (bc::is_little_endian)
     {
+        // This optimization is neutral in 4/8 lane sha256 perf.
         ////if constexpr (have_lanes<word_t, 8> && !with_clang)
         ////{
         ////    using xword_t = to_extended<word_t, 8>;
@@ -248,6 +251,7 @@ output(const state_t& state) NOEXCEPT
     {
         if constexpr (SHA::strength != 160)
         {
+            // This optimization is neutral in 4/8 lane sha256 perf.
             ////if constexpr (have_lanes<word_t, 8> && !with_clang)
             ////{
             ////    using xword_t = to_extended<word_t, 8>;
@@ -306,7 +310,7 @@ output(const state_t& state) NOEXCEPT
 
 TEMPLATE
 INLINE constexpr void CLASS::
-reinput_left(auto& buffer, const auto& left) NOEXCEPT
+inject_left(auto& buffer, const auto& left) NOEXCEPT
 {
     using words = decltype(buffer);
     static_assert(array_count<words> >= SHA::state_words);
@@ -331,7 +335,7 @@ reinput_left(auto& buffer, const auto& left) NOEXCEPT
 
 TEMPLATE
 INLINE constexpr void CLASS::
-reinput_right(auto& buffer, const auto& right) NOEXCEPT
+inject_right(auto& buffer, const auto& right) NOEXCEPT
 {
     using words = decltype(buffer);
     static_assert(array_count<words> >= SHA::state_words);
diff --git a/include/bitcoin/system/impl/hash/sha/algorithm_single.ipp b/include/bitcoin/system/impl/hash/sha/algorithm_single.ipp
index 9e27cf11cb..af11afcddb 100644
--- a/include/bitcoin/system/impl/hash/sha/algorithm_single.ipp
+++ b/include/bitcoin/system/impl/hash/sha/algorithm_single.ipp
@@ -62,7 +62,7 @@ TEMPLATE
 constexpr typename CLASS::digest_t CLASS::
 hash(const half_t& half) NOEXCEPT
 {
-    const auto hash1 = [](const half_t& half) NOEXCEPT
+    const auto hasher = [](const half_t& half) NOEXCEPT
     {
         auto state = H::get;
         buffer_t buffer{};
@@ -75,7 +75,7 @@ hash(const half_t& half) NOEXCEPT
 
     if (std::is_constant_evaluated())
     {
-        return hash1(half);
+        return hasher(half);
     }
     else if constexpr (native && SHA::strength == 256)
     {
@@ -83,7 +83,7 @@ hash(const half_t& half) NOEXCEPT
     }
     else
     {
-        return hash1(half);
+        return hasher(half);
     }
 }
 
@@ -91,7 +91,7 @@ TEMPLATE
 constexpr typename CLASS::digest_t CLASS::
 hash(const half_t& left, const half_t& right) NOEXCEPT
 {
-    const auto hash1 = [](const half_t& left, const half_t& right) NOEXCEPT
+    const auto hasher = [](const half_t& left, const half_t& right) NOEXCEPT
     {
         auto state = H::get;
         buffer_t buffer{};
@@ -106,7 +106,7 @@ hash(const half_t& left, const half_t& right) NOEXCEPT
 
     if (std::is_constant_evaluated())
     {
-        return hash1(left, right);
+        return hasher(left, right);
     }
     else if constexpr (native && SHA::strength == 256)
     {
@@ -114,7 +114,7 @@ hash(const half_t& left, const half_t& right) NOEXCEPT
     }
     else
     {
-        return hash1(left, right);
+        return hasher(left, right);
     }
 }
 
diff --git a/include/bitcoin/system/impl/hash/sha/algorithm_stream.ipp b/include/bitcoin/system/impl/hash/sha/algorithm_stream.ipp
index a018fae98d..9e56b423fd 100644
--- a/include/bitcoin/system/impl/hash/sha/algorithm_stream.ipp
+++ b/include/bitcoin/system/impl/hash/sha/algorithm_stream.ipp
@@ -116,7 +116,7 @@ finalize_second(const state_t& state) NOEXCEPT
     {
         auto state2 = H::get;
         buffer_t buffer{};
-        reinput_left(buffer, state);
+        inject_left(buffer, state);
         pad_half(buffer);
         schedule(buffer);
         compress(state2, buffer);
@@ -150,7 +150,7 @@ finalize_double(state_t& state, size_t blocks) NOEXCEPT
 
         // This is finalize_second() but reuses the initial buffer.
         auto state2 = H::get;
-        reinput_left(buffer, state);
+        inject_left(buffer, state);
         pad_half(buffer);
         schedule(buffer);
         compress(state2, buffer);