diff --git a/builds/msvc/vs2022/libbitcoin-system.import.props b/builds/msvc/vs2022/libbitcoin-system.import.props
index 390dc00393..bb11eeb347 100644
--- a/builds/msvc/vs2022/libbitcoin-system.import.props
+++ b/builds/msvc/vs2022/libbitcoin-system.import.props
@@ -51,8 +51,7 @@
       <!-- WIN32_LEAN_AND_MEAN avoids inclusion of certain headers, winsock.h conflicts with boost and protocol use of winsock2.h. -->
       <PreprocessorDefinitions>WITH_ICU;WIN32_LEAN_AND_MEAN;NOMINMAX;_WIN32_WINNT=0x0600;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(Linkage-libbitcoin-system)' == 'static' Or '$(Linkage-libbitcoin-system)' == 'ltcg'">BC_STATIC;%(PreprocessorDefinitions)</PreprocessorDefinitions>
-    </ClCompile>
-    <ClCompile>
+      <PreprocessorDefinitions Condition="$(Configuration.IndexOf('Debug')) != -1">_CRTDBG_MAP_ALLOC;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <!-- Enable use of CPU intrinsics. -->
       <PreprocessorDefinitions Condition="'$(Option-avx512)' == 'true'">WITH_AVX512;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(Option-avx2)'   == 'true'">WITH_AVX2;%(PreprocessorDefinitions)</PreprocessorDefinitions>
diff --git a/builds/msvc/vs2022/libbitcoin-system/libbitcoin-system.props b/builds/msvc/vs2022/libbitcoin-system/libbitcoin-system.props
index 3bf5c75a6e..bc258cc4e9 100644
--- a/builds/msvc/vs2022/libbitcoin-system/libbitcoin-system.props
+++ b/builds/msvc/vs2022/libbitcoin-system/libbitcoin-system.props
@@ -25,6 +25,7 @@
       <PreprocessorDefinitions>WITH_ICU;WIN32_LEAN_AND_MEAN;NOMINMAX;_WIN32_WINNT=0x0600;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(ConfigurationType)' == 'DynamicLibrary'">BC_DLL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(ConfigurationType)' == 'StaticLibrary'">BC_STATIC;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions Condition="$(Configuration.IndexOf('Debug')) != -1">_CRTDBG_MAP_ALLOC;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <!-- Enable use of CPU intrinsics. -->
       <PreprocessorDefinitions Condition="'$(Option-avx512)' == 'true'">WITH_AVX512;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(Option-avx2)'   == 'true'">WITH_AVX2;%(PreprocessorDefinitions)</PreprocessorDefinitions>
diff --git a/include/bitcoin/system/have.hpp b/include/bitcoin/system/have.hpp
index 31ed4f9758..ac4eccd62c 100644
--- a/include/bitcoin/system/have.hpp
+++ b/include/bitcoin/system/have.hpp
@@ -128,10 +128,10 @@
     #define HAVE_ICU
 #endif
 
-/// XCPU architecture intrinsics sse41, avx2, avx512f, sha-ni.
+/// XCPU architecture intrinsics sse41, avx2, avx512f/bw, sha-ni.
 /// This assumes that avx512 implies avx2 and that all imply sse41.
 #if defined(HAVE_XCPU)
-    // TODO: CLANG/GCC compile test and set -msse4 -mavx2 -mavx512f -msha.
+    // CLANG/GCC compile with -msse4 -mavx2 -mavx512f/-mavx512bw -msha.
     #if defined(WITH_SHANI)
         #define HAVE_SHANI
     #endif
@@ -204,9 +204,6 @@
     #endif
 #endif
 
-/// C++20: parenthesized initialization of aggregates requires clang16/xcode16.
-/// We don't have macro treatment for that, just ad-hoc HAVE_CLANG conditions.
-
 /// None on xcode.
 /// Requires link with -ltbb on gcc (v9).
 /// Experimental on clang (libcxx.llvm.org/Status/PSTL.html), requires:
@@ -227,7 +224,7 @@
 #define HAVE_SUPPRESSION
 
 /// Disable noexcept to capture stack trace.
-#define HAVE_NOEXCEPT
+////#define HAVE_NOEXCEPT
 
 /// Disable to emit all suppressed warnings.
 #define HAVE_WARNINGS
diff --git a/include/bitcoin/system/intrinsics/haves.hpp b/include/bitcoin/system/intrinsics/haves.hpp
index 282c84f5e8..3e206dc5db 100644
--- a/include/bitcoin/system/intrinsics/haves.hpp
+++ b/include/bitcoin/system/intrinsics/haves.hpp
@@ -74,7 +74,6 @@ namespace cpu1_0
     constexpr auto avx_ecx_bit = 28;
 }
 
-// wikichip.org/wiki/x86/avx-512
 namespace cpu7_0
 {
     constexpr auto leaf = 7;
diff --git a/include/bitcoin/system/literals.hpp b/include/bitcoin/system/literals.hpp
index d94fd83197..60560fe888 100644
--- a/include/bitcoin/system/literals.hpp
+++ b/include/bitcoin/system/literals.hpp
@@ -35,7 +35,7 @@ namespace libbitcoin {
 /// not be subject to regressions in other code, as a break here causes a large
 /// number of test and other failures. See tests for usage and detailed info.
 /// ---------------------------------------------------------------------------
-/// These should be consteval for safety, but waiting on clang++20 to catch up.
+/// These should be consteval for safety, but waiting on clang++ v17.
 
 // Functions are consteval where available (bogus warning).
 BC_PUSH_WARNING(USE_CONSTEXPR_FOR_FUNCTION)
diff --git a/include/bitcoin/system/preprocessor.hpp b/include/bitcoin/system/preprocessor.hpp
index f3808b8bca..ccade62d24 100644
--- a/include/bitcoin/system/preprocessor.hpp
+++ b/include/bitcoin/system/preprocessor.hpp
@@ -32,6 +32,22 @@
 /// Debugging.
 /// ---------------------------------------------------------------------------
 
+/// Enables ETW tracing for VS memory profiler.
+#if defined(HAVE_MSC)
+    #define ALLOCATOR __declspec(allocator)
+#else
+    #define ALLOCATOR
+#endif
+
+/// learn.microsoft.com/en-us/cpp/c-runtime-library/
+/// find-memory-leaks-using-the-crt-library
+/// _CRTDBG_MAP_ALLOC must be prior to the includes, so defined in props.
+#if defined(HAVE_MSC) && defined(_DEBUG) && defined(_CRTDBG_MAP_ALLOC)
+    #include <stdlib.h>
+    #include <crtdbg.h>
+    ////_CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);
+#endif
+
 /// NDEBUG (conditional exclusion).
 #if defined(NDEBUG)
     #define BC_ASSERT(expression)
@@ -44,13 +60,6 @@
     #define BC_DEBUG_ONLY(expression) expression
 #endif
 
-/// Enables ETW tracing for VS memory profiler.
-#if defined(HAVE_MSC)
-    #define ALLOCATOR __declspec(allocator)
-#else
-    #define ALLOCATOR
-#endif
-
 /// Messages.
 /// ---------------------------------------------------------------------------
 
diff --git a/src/arena.cpp b/src/arena.cpp
index 936b868fe2..1ea64cf81f 100644
--- a/src/arena.cpp
+++ b/src/arena.cpp
@@ -18,12 +18,11 @@
  */
 #include <bitcoin/system/arena.hpp>
 
+#include <cstdlib>
 #include <bitcoin/system/constants.hpp>
 
 namespace libbitcoin {
 
-BC_PUSH_WARNING(NO_NEW_OR_DELETE)
-
 bool operator==(const arena& left, const arena& right) NOEXCEPT
 {
     return &left == &right || left.is_equal(right);
@@ -41,14 +40,18 @@ void* default_arena::do_allocate(size_t bytes, size_t) THROWS
 {
     ////if (align > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
     ////    return ::operator new(bytes, std::align_val_t{ align });
-    return ::operator new(bytes);
+    BC_PUSH_WARNING(NO_MALLOC_OR_FREE)
+    return std::malloc(bytes);
+    BC_POP_WARNING()
 }
 
 void default_arena::do_deallocate(void* ptr, size_t, size_t) NOEXCEPT
 {
     ////if (align > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
     ////    ::operator delete(ptr, std::align_val_t{ align });
-    ::operator delete(ptr);
+    BC_PUSH_WARNING(NO_MALLOC_OR_FREE)
+    std::free(ptr);
+    BC_POP_WARNING()
 }
 
 bool default_arena::do_is_equal(const arena& other) const NOEXCEPT
@@ -57,6 +60,7 @@ bool default_arena::do_is_equal(const arena& other) const NOEXCEPT
     return &other == this;
 }
 
+// null return indicates that this arena is not detachable.
 void* default_arena::start(size_t) THROWS
 {
     return nullptr;
@@ -71,6 +75,4 @@ void default_arena::release(void*) NOEXCEPT
 {
 }
 
-BC_POP_WARNING()
-
 } // namespace libbitcoin
diff --git a/src/chain/block.cpp b/src/chain/block.cpp
index 31c05c7f5a..0a750b596f 100644
--- a/src/chain/block.cpp
+++ b/src/chain/block.cpp
@@ -20,7 +20,6 @@
 
 #include <algorithm>
 #include <iterator>
-#include <memory>
 #include <numeric>
 #include <ranges>
 #include <set>
diff --git a/src/chain/point.cpp b/src/chain/point.cpp
index 05fa87f309..9d9c29dbcf 100644
--- a/src/chain/point.cpp
+++ b/src/chain/point.cpp
@@ -18,7 +18,6 @@
  */
 #include <bitcoin/system/chain/point.hpp>
 
-#include <memory>
 #include <utility>
 #include <bitcoin/system/chain/enums/magic_numbers.hpp>
 #include <bitcoin/system/define.hpp>
diff --git a/src/chain/script.cpp b/src/chain/script.cpp
index b0384cdad8..bc06d44521 100644
--- a/src/chain/script.cpp
+++ b/src/chain/script.cpp
@@ -20,7 +20,6 @@
 
 #include <algorithm>
 #include <iterator>
-#include <memory>
 #include <numeric>
 #include <sstream>
 #include <utility>
diff --git a/src/chain/transaction.cpp b/src/chain/transaction.cpp
index f90f6ad928..7a6da3ac44 100644
--- a/src/chain/transaction.cpp
+++ b/src/chain/transaction.cpp
@@ -20,7 +20,6 @@
 
 #include <algorithm>
 #include <iterator>
-#include <memory>
 #include <numeric>
 #include <type_traits>
 #include <utility>
diff --git a/test/allocator.cpp b/test/allocator.cpp
index 88f0ff1f62..5ade65cc17 100644
--- a/test/allocator.cpp
+++ b/test/allocator.cpp
@@ -26,10 +26,6 @@ BC_PUSH_WARNING(NO_UNGUARDED_POINTERS)
 BC_PUSH_WARNING(NO_DELETE_RAW_POINTER)
 BC_PUSH_WARNING(NO_UNCLEARED_OWNER_POINTER)
 
-// Clang is not yet C++20 compliant in terms of aggregate initialization.
-// See [reviews.llvm.org/D140327] for details. So vectors provide constructors.
-///////////////////////////////////////////////////////////////////////////////
-
 struct simple
 {
     simple(size_t arg={}) NOEXCEPT