diff --git a/performance.xlsx b/performance.xlsx
index d188121..997d170 100644
Binary files a/performance.xlsx and b/performance.xlsx differ
diff --git a/src/circ/elem_def.h b/src/circ/elem_def.h
index ac432c8..c0ea326 100644
--- a/src/circ/elem_def.h
+++ b/src/circ/elem_def.h
@@ -12,10 +12,6 @@
 namespace ipc {
 namespace circ {
 
-enum {
-    cache_line_size = 64
-};
-
 using u1_t = ipc::uint_t<8>;
 using u2_t = ipc::uint_t<32>;
 
diff --git a/src/ipc.cpp b/src/ipc.cpp
old mode 100755
new mode 100644
diff --git a/src/memory/alloc.h b/src/memory/alloc.h
index ace13a5..e055744 100644
--- a/src/memory/alloc.h
+++ b/src/memory/alloc.h
@@ -2,9 +2,6 @@
 
 #include <algorithm>
 #include <utility>
-#include <atomic>
-#include <thread>
-#include <mutex>
 #include <cstdlib>
 
 #include "def.h"
@@ -31,10 +28,6 @@ public:
     static void free(void* p, std::size_t /*size*/) {
         free(p);
     }
-
-    static std::size_t size_of(void* /*p*/) {
-        return 0;
-    }
 };
 
 ////////////////////////////////////////////////////////////////
@@ -54,8 +47,8 @@ public:
     void free(void* /*p*/) {}
     void free(void* /*p*/, std::size_t) {}
 
-    constexpr std::size_t size_of(void* /*p*/) const {
-        return 0;
+    void swap(scope_alloc_base & rhs) {
+        std::swap(this->list_, rhs.list_);
     }
 };
 
@@ -64,6 +57,7 @@ public:
 template <typename AllocP = static_alloc>
 class scope_alloc : public detail::scope_alloc_base {
 public:
+    using base_t = detail::scope_alloc_base;
     using alloc_policy = AllocP;
 
 private:
@@ -80,7 +74,7 @@ public:
 public:
     void swap(scope_alloc& rhs) {
         std::swap(this->alloc_, rhs.alloc_);
-        std::swap(this->list_ , rhs.list_);
+        base_t::swap(rhs);
     }
 
     void clear() {
@@ -106,6 +100,14 @@ public:
 
 namespace detail {
 
+template <std::size_t BlockSize>
+struct fixed_expand_policy {
+    static std::size_t next(std::size_t & e) {
+        static constexpr std::size_t basic_size = (ipc::detail::max)(BlockSize, static_cast<std::size_t>(2048));
+        return basic_size * (e *= 2);
+    }
+};
+
 class fixed_alloc_base {
 protected:
     std::size_t init_expand_;
@@ -113,7 +115,7 @@ protected:
 
     void init(std::size_t init_expand) {
         init_expand_ = init_expand;
-        cursor_ = nullptr;
+        cursor_      = nullptr;
     }
 
     static void** node_p(void* node) {
@@ -127,7 +129,7 @@ protected:
 public:
     void swap(fixed_alloc_base& rhs) {
         std::swap(this->init_expand_, rhs.init_expand_);
-        std::swap(this->cursor_     , rhs.cursor_     );
+        std::swap(this->cursor_     , rhs.cursor_);
     }
 
     void free(void* p) {
@@ -143,7 +145,7 @@ public:
 
 } // namespace detail
 
-template <std::size_t BlockSize, typename AllocP = scope_alloc<>>
+template <std::size_t BlockSize, template <std::size_t> class ExpandP = detail::fixed_expand_policy, typename AllocP = scope_alloc<>>
 class fixed_alloc : public detail::fixed_alloc_base {
 public:
     using base_t = detail::fixed_alloc_base;
@@ -160,9 +162,9 @@ private:
         if (this->cursor_ != nullptr) {
             return this->cursor_;
         }
-        auto p = this->node_p(this->cursor_ = alloc_.alloc(block_size));
-        auto size = alloc_.size_of(p);
-        if (size > 0) for (std::size_t i = 0; i < (size / block_size) - 1; ++i)
+        auto size = ExpandP<block_size>::next(this->init_expand_);
+        auto p = this->node_p(this->cursor_ = alloc_.alloc(size));
+        for (std::size_t i = 0; i < (size / block_size) - 1; ++i)
             p = this->node_p((*p) = reinterpret_cast<byte_t*>(p) + block_size);
         (*p) = nullptr;
         return this->cursor_;
@@ -187,10 +189,6 @@ public:
         this->init(this->init_expand_);
     }
 
-    constexpr std::size_t size_of(void* /*p*/) const {
-        return block_size;
-    }
-
     void* alloc() {
         void* p = try_expand();
         this->cursor_ = this->next(p);
@@ -202,14 +200,5 @@ public:
     }
 };
 
-////////////////////////////////////////////////////////////////
-/// page memory allocation
-////////////////////////////////////////////////////////////////
-
-using page_alloc = fixed_alloc<4096>;
-
-template <std::size_t BlockSize>
-using page_fixed_alloc = fixed_alloc<BlockSize, page_alloc>;
-
 } // namespace mem
 } // namespace ipc
diff --git a/src/memory/detail.h b/src/memory/detail.h
index 90748e1..a654f6b 100644
--- a/src/memory/detail.h
+++ b/src/memory/detail.h
@@ -13,14 +13,6 @@ enum : std::size_t {
     base_size = sizeof(void*)
 };
 
-template <std::size_t Size, template <std::size_t> class FixedAlloc>
-struct fixed {
-    static auto& pool() {
-        static FixedAlloc<Size> pool;
-        return pool;
-    }
-};
-
 #if __cplusplus >= 201703L
 constexpr std::size_t classify(std::size_t size) {
     constexpr std::size_t mapping[] = {
@@ -51,18 +43,18 @@ inline std::size_t classify(std::size_t size) {
 template <template <std::size_t> class Fixed, typename F>
 decltype(auto) choose(std::size_t size, F&& f) {
     return ipc::detail::static_switch<32>(classify(size), [&f](auto index) {
-        return f(Fixed<(decltype(index)::value + 1) * base_size>::pool());
+        return f(Fixed<(decltype(index)::value + 1) * base_size>::instance());
     }, [&f] {
         return f(static_alloc{});
     });
 }
 
 template <template <std::size_t> class Fixed>
-class pool_alloc {
+class fixed_alloc_policy {
 public:
     static void clear() {
         ipc::detail::static_for<32>([](auto index) {
-            Fixed<(decltype(index)::value + 1) * base_size>::pool().clear();
+            Fixed<(decltype(index)::value + 1) * base_size>::instance().clear();
         });
     }
 
diff --git a/src/memory/resource.h b/src/memory/resource.h
old mode 100755
new mode 100644
index d30cb17..627f968
--- a/src/memory/resource.h
+++ b/src/memory/resource.h
@@ -19,15 +19,11 @@ namespace ipc {
 namespace mem {
 
 template <std::size_t Size>
-using sync_fixed_alloc = mem::synchronized<page_fixed_alloc<Size>>;
-
-template <std::size_t Size>
-using sync_fixed = mem::detail::fixed<Size, sync_fixed_alloc>;
-
-using sync_pool_alloc = mem::detail::pool_alloc<sync_fixed>;
+using static_async_fixed = mem::static_wrapper<mem::async_wrapper<mem::fixed_alloc<Size>>>;
+using async_pool_alloc   = mem::detail::fixed_alloc_policy<static_async_fixed>;
 
 template <typename T>
-using allocator = allocator_wrapper<T, sync_pool_alloc>;
+using allocator = allocator_wrapper<T, async_pool_alloc>;
 
 } // namespace mem
 
diff --git a/src/memory/wrapper.h b/src/memory/wrapper.h
index 6d602ac..8a49e38 100644
--- a/src/memory/wrapper.h
+++ b/src/memory/wrapper.h
@@ -3,7 +3,7 @@
 #include <limits>
 #include <new>
 #include <tuple>
-#include <map>
+#include <thread>
 #include <vector>
 #include <functional>
 #include <utility>
@@ -128,76 +128,62 @@ constexpr bool operator!=(const allocator_wrapper<T, AllocP>&, const allocator_w
 ////////////////////////////////////////////////////////////////
 
 template <typename AllocP>
-class synchronized {
+class async_wrapper {
 public:
     using alloc_policy = AllocP;
 
 private:
-    spin_lock lc_;
-    std::multimap<std::size_t, alloc_policy*> allocs_;
+    class alloc_proxy : public alloc_policy {
+        async_wrapper * w_ = nullptr;
 
-    struct alloc_t {
-        synchronized* t_;
-        std::size_t   s_ = 0;
-        alloc_policy* a_ = nullptr;
+    public:
+        alloc_proxy(alloc_proxy&& rhs)
+            : alloc_policy(std::move(rhs))
+        {}
 
-        alloc_t(synchronized* t)
-            : t_ { t } {
-            {
-                IPC_UNUSED_ auto guard = ipc::detail::unique_lock(t_->lc_);
-                auto it = t_->allocs_.begin();
-                if (it != t_->allocs_.end()) {
-                    std::tie(s_, a_) = *it;
-                    t_->allocs_.erase(it);
-                }
-            }
-            if (a_ == nullptr) {
-                a_ = new alloc_policy;
+        alloc_proxy(async_wrapper* w)
+            : alloc_policy(), w_(w) {
+            if (w_ == nullptr) return;
+            IPC_UNUSED_ auto guard = ipc::detail::unique_lock(w_->master_lock_);
+            if (!w_->master_allocs_.empty()) {
+                alloc_policy::swap(w_->master_allocs_.back());
+                w_->master_allocs_.pop_back();
             }
         }
 
-        ~alloc_t() {
-            IPC_UNUSED_ auto guard = ipc::detail::unique_lock(t_->lc_);
-            t_->allocs_.emplace(s_, a_);
-        }
-
-        void* alloc(std::size_t size) {
-            void* p = a_->alloc(size);
-            if ((p != nullptr) && (s_ > 0)) {
-                --s_;
-            }
-            return p;
-        }
-
-        void free(void* p) {
-            a_->free(p);
-            ++s_;
+        ~alloc_proxy() {
+            if (w_ == nullptr) return;
+            IPC_UNUSED_ auto guard = ipc::detail::unique_lock(w_->master_lock_);
+            w_->master_allocs_.emplace_back(std::move(*this));
         }
     };
 
-    auto& alc_info() {
-        static tls::pointer<alloc_t> alc;
-        return *alc.create(this);
+    friend class alloc_proxy;
+
+    spin_lock master_lock_;
+    std::vector<alloc_proxy> master_allocs_;
+
+    auto& get_alloc() {
+        static tls::pointer<alloc_proxy> tls_alc;
+        return *tls_alc.create(this);
     }
 
 public:
-    ~synchronized() {
+    ~async_wrapper() {
         clear();
     }
 
     void clear() {
-        IPC_UNUSED_ auto guard = ipc::detail::unique_lock(lc_);
-        for (auto& pair : allocs_) {
-            delete pair.second;
-        }
+        IPC_UNUSED_ auto guard = ipc::detail::unique_lock(master_lock_);
+        master_allocs_.clear();
     }
 
     void* alloc(std::size_t size) {
-        return alc_info().alloc(size);
+        return get_alloc().alloc(size);
     }
 
     void free(void* p) {
-        alc_info().free(p);
+        get_alloc().free(p);
     }
 
     void free(void* p, std::size_t /*size*/) {
@@ -210,7 +196,7 @@ public:
 ////////////////////////////////////////////////////////////////
 
 template <typename AllocP>
-class statical {
+class static_wrapper {
 public:
     using alloc_policy = AllocP;
 
diff --git a/src/platform/detail.h b/src/platform/detail.h
index 4f6e723..4daca2b 100644
--- a/src/platform/detail.h
+++ b/src/platform/detail.h
@@ -8,6 +8,7 @@
 #include <atomic>
 #include <algorithm>
 #include <utility>
+#include <new>
 
 #include "def.h"
 #include "export.h"
@@ -137,5 +138,14 @@ inline void static_for(F&& f) {
     static_for(std::make_index_sequence<N>{}, std::forward<F>(f));
 }
 
+// Minimum offset between two objects to avoid false sharing.
+enum {
+// #if __cplusplus >= 201703L
+//     cache_line_size = std::hardware_destructive_interference_size
+// #else /*__cplusplus < 201703L*/
+    cache_line_size = 64
+// #endif/*__cplusplus < 201703L*/
+};
+
 } // namespace detail
 } // namespace ipc
diff --git a/src/pool_alloc.cpp b/src/pool_alloc.cpp
index 1e7faca..cd83fdc 100644
--- a/src/pool_alloc.cpp
+++ b/src/pool_alloc.cpp
@@ -6,15 +6,15 @@ namespace ipc {
 namespace mem {
 
 void pool_alloc::clear() {
-    sync_pool_alloc::clear();
+    async_pool_alloc::clear();
 }
 
 void* pool_alloc::alloc(std::size_t size) {
-    return sync_pool_alloc::alloc(size);
+    return async_pool_alloc::alloc(size);
 }
 
 void pool_alloc::free(void* p, std::size_t size) {
-    sync_pool_alloc::free(p, size);
+    async_pool_alloc::free(p, size);
 }
 
 } // namespace mem
diff --git a/src/prod_cons.h b/src/prod_cons.h
index 016f465..0038625 100644
--- a/src/prod_cons.h
+++ b/src/prod_cons.h
@@ -26,8 +26,8 @@ struct prod_cons_impl<wr<relat::single, relat::single, trans::unicast>> {
         std::aligned_storage_t<DataSize, AlignSize> data_ {};
     };
 
-    alignas(circ::cache_line_size) std::atomic<circ::u2_t> rd_; // read index
-    alignas(circ::cache_line_size) std::atomic<circ::u2_t> wt_; // write index
+    alignas(detail::cache_line_size) std::atomic<circ::u2_t> rd_; // read index
+    alignas(detail::cache_line_size) std::atomic<circ::u2_t> wt_; // write index
 
     constexpr circ::u2_t cursor() const noexcept {
         return 0;
@@ -96,7 +96,7 @@ struct prod_cons_impl<wr<relat::multi , relat::multi, trans::unicast>>
         std::atomic<flag_t> f_ct_ { 0 }; // commit flag
     };
 
-    alignas(circ::cache_line_size) std::atomic<circ::u2_t> ct_; // commit index
+    alignas(detail::cache_line_size) std::atomic<circ::u2_t> ct_; // commit index
 
     template <typename W, typename F, typename E>
     bool push(W* /*wrapper*/, F&& f, E* elems) {
@@ -182,7 +182,7 @@ struct prod_cons_impl<wr<relat::single, relat::multi, trans::broadcast>> {
         std::atomic<rc_t> rc_ { 0 }; // read-counter
     };
 
-    alignas(circ::cache_line_size) std::atomic<circ::u2_t> wt_; // write index
+    alignas(detail::cache_line_size) std::atomic<circ::u2_t> wt_; // write index
 
     circ::u2_t cursor() const noexcept {
         return wt_.load(std::memory_order_acquire);
@@ -276,7 +276,7 @@ struct prod_cons_impl<wr<relat::multi , relat::multi, trans::broadcast>> {
         std::atomic<flag_t> f_ct_ { 0 }; // commit flag
     };
 
-    alignas(circ::cache_line_size) std::atomic<circ::u2_t> ct_; // commit index
+    alignas(detail::cache_line_size) std::atomic<circ::u2_t> ct_; // commit index
 
     circ::u2_t cursor() const noexcept {
         return ct_.load(std::memory_order_acquire);
diff --git a/test/test_circ.cpp b/test/test_circ.cpp
index bdf6b7d..2e10e50 100644
--- a/test/test_circ.cpp
+++ b/test/test_circ.cpp
@@ -238,7 +238,7 @@ private slots:
     void test_prod_cons_1v3();
     void test_prod_cons_performance();
     void test_queue();
-} /*unit__*/;
+} unit__;
 
 #include "test_circ.moc"
 
diff --git a/test/test_mem.cpp b/test/test_mem.cpp
index b587f6f..f36d92d 100644
--- a/test/test_mem.cpp
+++ b/test/test_mem.cpp
@@ -23,14 +23,15 @@ private slots:
     void initTestCase();
 
     void test_alloc_free();
-    void test_linear();
-} /*unit__*/;
+    void test_static();
+    void test_pool();
+} unit__;
 
 #include "test_mem.moc"
 
 constexpr int DataMin   = sizeof(void*);
 constexpr int DataMax   = sizeof(void*) * 16;
-constexpr int LoopCount = 1000000;
+constexpr int LoopCount = 10000000;
 
 std::vector<std::size_t> sizes__;
 
@@ -106,7 +107,7 @@ void benchmark_alloc() {
 
 void Unit::test_alloc_free() {
     benchmark_alloc<ipc::mem::static_alloc>();
-    benchmark_alloc<ipc::mem::sync_pool_alloc>();
+    benchmark_alloc<ipc::mem::async_pool_alloc>();
 }
 
 template <typename AllocT, typename ModeT, int ThreadsN>
@@ -145,7 +146,7 @@ void benchmark_alloc() {
                 }
             }
             if ((fini.fetch_add(1, std::memory_order_relaxed) + 1) == ThreadsN) {
-                sw.print_elapsed<1>(DataMin, DataMax, LoopCount);
+                sw.print_elapsed<1>(DataMin, DataMax, LoopCount * ThreadsN);
             }
         }};
         ++pid;
@@ -170,15 +171,16 @@ struct test_performance<AllocT, ModeT, 1> {
     }
 };
 
-void Unit::test_linear() {
-    test_performance<ipc::mem::static_alloc, alloc_random, 8>::start();
-    test_performance<ipc::mem::pool_alloc  , alloc_random, 8>::start();
-
-    test_performance<ipc::mem::static_alloc, alloc_LIFO  , 8>::start();
-    test_performance<ipc::mem::pool_alloc  , alloc_LIFO  , 8>::start();
-
+void Unit::test_static() {
     test_performance<ipc::mem::static_alloc, alloc_FIFO  , 8>::start();
-    test_performance<ipc::mem::pool_alloc  , alloc_FIFO  , 8>::start();
+    test_performance<ipc::mem::static_alloc, alloc_LIFO  , 8>::start();
+    test_performance<ipc::mem::static_alloc, alloc_random, 8>::start();
+}
+
+void Unit::test_pool() {
+    test_performance<ipc::mem::pool_alloc, alloc_FIFO  , 8>::start();
+    test_performance<ipc::mem::pool_alloc, alloc_LIFO  , 8>::start();
+    test_performance<ipc::mem::pool_alloc, alloc_random, 8>::start();
 }
 
 } // internal-linkage