diff --git a/include/another-rxcpp/internal/tools/stream_controller.h b/include/another-rxcpp/internal/tools/stream_controller.h
index 7a80110..3c9082f 100644
--- a/include/another-rxcpp/internal/tools/stream_controller.h
+++ b/include/another-rxcpp/internal/tools/stream_controller.h
@@ -25,7 +25,7 @@ template <typename T> class stream_controller {
     serial_type           serial_;
     unsubscriber_map      unsubscribers_;
     on_finalizes_t        on_finalizes_;
-    inner(const subscriber_type& sbsc) : subscriber_(sbsc) {}
+    inner(const subscriber_type& sbsc) noexcept : subscriber_(sbsc), serial_(0) {}
   };
 
   mutable std::shared_ptr<inner> inner_;
@@ -33,6 +33,8 @@ template <typename T> class stream_controller {
   stream_controller(std::shared_ptr<inner> inner) noexcept
   : inner_(inner) {}
 
+  stream_controller() = delete;
+
 public:
   stream_controller(const subscriber_type& subscriber) noexcept {
     inner_ = std::make_shared<inner>(subscriber);
@@ -41,14 +43,9 @@ template <typename T> class stream_controller {
     });
   }
 
-  void set_on_finalize(const on_finalize_t& f) const noexcept {
-    std::lock_guard<std::recursive_mutex> lock(inner_->mtx_);
-    inner_->on_finalizes_.push(f);
-  }
-
-  void set_on_finalize(on_finalize_t&& f) const noexcept {
+  template <typename F> void set_on_finalize(F&& f) const noexcept {
     std::lock_guard<std::recursive_mutex> lock(inner_->mtx_);
-    inner_->on_finalizes_.reset(new on_finalize_t(std::move(f)));
+    inner_->on_finalizes_ = std::make_shared<on_finalize_t>(std::forward<F>(f));
   }
 
   template <typename In> observer<In> new_observer(
diff --git a/include/another-rxcpp/internal/tools/util.h b/include/another-rxcpp/internal/tools/util.h
index 382b3f5..88c0d19 100644
--- a/include/another-rxcpp/internal/tools/util.h
+++ b/include/another-rxcpp/internal/tools/util.h
@@ -39,16 +39,6 @@ template <typename SP>
     return std::weak_ptr<typename SP::element_type>(sp);
   }
 
-template <typename T>
-  auto to_shared(T&& value) noexcept {
-    return std::make_shared<T>(std::forward<T>(value));
-  }
-
-template <typename T>
-  auto to_shared(const T& value) noexcept {
-    return std::make_shared<T>(value);
-  }
-
 }} /* namespace another_rxcpp::internal */
 
 #endif /* !defined(__another_rxcpp_h_util__) */
diff --git a/include/another-rxcpp/observable.h b/include/another-rxcpp/observable.h
index bbff7b1..3d480de 100644
--- a/include/another-rxcpp/observable.h
+++ b/include/another-rxcpp/observable.h
@@ -80,15 +80,13 @@ template <typename T> class observable {
     return subscribe(observer<value_type>(n, e, c));
   }
 
-  subscription subscribe(
-    next_t&&       n = {},
-    error_t&&      e = {},
-    completed_t&&  c = {}
-  ) const noexcept {
+  template <typename N, typename E, typename C>
+    subscription subscribe(N&& n, E&& e, C&& c) const noexcept
+  {
     return subscribe(observer<value_type>(
-      std::move(n),
-      std::move(e),
-      std::move(c)
+      std::forward<N>(n),
+      std::forward<E>(e),
+      std::forward<C>(c)
     ));
   }
 
diff --git a/include/another-rxcpp/observables/connectable.h b/include/another-rxcpp/observables/connectable.h
index dd6bd14..fcce094 100644
--- a/include/another-rxcpp/observables/connectable.h
+++ b/include/another-rxcpp/observables/connectable.h
@@ -34,8 +34,8 @@ friend class connectable<>;
     std::recursive_mutex  mtx_;
     serial_type           serial_;
     subscription          subscription_;
-    member(source_observable&& source): source_(std::move(source)) {}
-    member(const source_observable& source): source_(source) {}
+    member(source_observable&& source): source_(std::move(source)), serial_(0) {}
+    member(const source_observable& source): source_(source), serial_(0) {}
   };
   std::shared_ptr<member> m_;
 
@@ -90,31 +90,30 @@ friend class connectable<>;
 
     auto collect = [m](bool clear){
       std::lock_guard<std::recursive_mutex> lock(m->mtx_);
-      std::vector<observer_type> ret(m->observers_.size());
-      auto ret_it = ret.begin();
-      for(auto it = m->observers_.begin(); it != m->observers_.end(); it++, ret_it++){
-        *ret_it = it->second;
-      }
+      std::vector<observer_type> ret;
+      std::for_each(m->observers_.begin(), m->observers_.end(), [&ret](auto& it){
+        ret.push_back(it.second);
+      });
       if(clear) m->observers_.clear();
       return ret;
     };
 
     auto sbsc = m->source_.subscribe(
-      [collect](value_type x) {
+      [collect](const value_type& x) {
         auto obs = collect(false);
-        std::for_each(obs.begin(), obs.end(), [&](auto ob){
+        std::for_each(obs.begin(), obs.end(), [&x](auto& ob){
           ob.on_next(x);
         });
       },
       [collect](std::exception_ptr err){
         auto obs = collect(true);
-        std::for_each(obs.begin(), obs.end(), [&](auto ob){
+        std::for_each(obs.begin(), obs.end(), [&err](auto& ob){
           ob.on_error(err);
         });
       },
       [collect](){
         auto obs = collect(true);
-        std::for_each(obs.begin(), obs.end(), [&](auto ob){
+        std::for_each(obs.begin(), obs.end(), [](auto& ob){
           ob.on_completed();
         });
       }
diff --git a/include/another-rxcpp/observer.h b/include/another-rxcpp/observer.h
index 2be2439..b9ed547 100644
--- a/include/another-rxcpp/observer.h
+++ b/include/another-rxcpp/observer.h
@@ -3,7 +3,7 @@
 
 #include <functional>
 #include <memory>
-#include <optional>
+#include <mutex>
 #include "internal/tools/fn.h"
 #include "internal/tools/util.h"
 
@@ -36,6 +36,7 @@ template <typename T> struct observer {
 
 private:
   struct inner {
+    std::recursive_mutex  mtx_;
     next_sp        next_;
     error_sp       error_;
     completed_sp   completed_;
@@ -46,45 +47,35 @@ template <typename T> struct observer {
 
   friend class internal::stream_controller<T>;
 
-  void set_on_unsubscribe(const unsubscribe_t& f) const noexcept {
-    inner_->unsubscribe_ = internal::to_shared(f);
+  template <typename Unsb> void set_on_unsubscribe(Unsb&& f) const noexcept {
+    inner_->unsubscribe_ = std::make_shared<unsubscribe_t>(std::forward<Unsb>(f));
   }
 
-  void set_on_unsubscribe(unsubscribe_t&& f) const noexcept {
-    inner_->unsubscribe_ = internal::to_shared(std::move(f));
+  auto fetch_and_reset_all() const noexcept {
+    std::lock_guard<std::recursive_mutex> lock(inner_->mtx_);
+    auto e = inner_->error_;
+    auto c = inner_->completed_;
+    auto u = inner_->unsubscribe_;
+    inner_->next_.reset();
+    inner_->error_.reset();
+    inner_->completed_.reset();
+    inner_->unsubscribe_.reset();
+    return std::make_tuple(e, c, u);
   }
 
-
 public:
-  observer(const next_t& n = {}, const error_t& e = {}, const completed_t& c = {}) noexcept {
+  template<typename N, typename E, typename C> observer(N&& n, E&& e, C&& c) noexcept {
     inner_ = std::make_shared<inner>();
-    inner_->next_       = internal::to_shared(n);
-    inner_->error_      = internal::to_shared(e);
-    inner_->completed_  = internal::to_shared(c);
+    inner_->next_       = std::make_shared<next_t>(std::forward<N>(n));
+    inner_->error_      = std::make_shared<error_t>(std::forward<E>(e));
+    inner_->completed_  = std::make_shared<completed_t>(std::forward<C>(c));
   }
 
-  observer(next_t&& n, error_t&& e, completed_t&& c) noexcept {
+  observer(const next_t& n = {}, const error_t& e = {}, const completed_t& c = {}) noexcept {
     inner_ = std::make_shared<inner>();
-    inner_->next_       = internal::to_shared(std::move(n));
-    inner_->error_      = internal::to_shared(std::move(e));
-    inner_->completed_  = internal::to_shared(std::move(c));
-  }
-
-  void unsubscribe() const noexcept {
-    auto unsb = inner_->unsubscribe_;
-
-    inner_->next_.reset();
-    inner_->error_.reset();
-    inner_->completed_.reset();
-    inner_->unsubscribe_.reset();
-    
-    if(unsb && *unsb) {
-      (*unsb)();
-    }
-  }
-
-  bool is_subscribed() const noexcept {
-    return inner_->next_ && inner_->error_ && inner_->completed_;
+    inner_->next_       = std::make_shared<next_t>(n);
+    inner_->error_      = std::make_shared<error_t>(e);
+    inner_->completed_  = std::make_shared<completed_t>(c);
   }
 
   void on_next(const value_type& value) const noexcept {
@@ -98,20 +89,30 @@ template <typename T> struct observer {
   }
 
   void on_error(std::exception_ptr err) const noexcept {
-    auto e = inner_->error_;
-    auto u = inner_->unsubscribe_;
-    unsubscribe();
+    auto ecu = fetch_and_reset_all();
+    auto e = std::get<0>(ecu);
+    auto u = std::get<2>(ecu);
     if(e && *e) (*e)(err);
     if(u && *u) (*u)();
   }
 
   void on_completed() const noexcept {
-    auto c = inner_->completed_;
-    auto u = inner_->unsubscribe_;
-    unsubscribe();
+    auto ecu = fetch_and_reset_all();
+    auto c = std::get<1>(ecu);
+    auto u = std::get<2>(ecu);
     if(c && *c) (*c)();
     if(u && *u) (*u)();
   }
+
+  void unsubscribe() const noexcept {
+    auto ecu = fetch_and_reset_all();
+    auto u = std::get<2>(ecu);
+    if(u && *u) (*u)();
+  }
+
+  bool is_subscribed() const noexcept {
+    return inner_->next_ && inner_->error_ && inner_->completed_;
+  }
 };
 
 } /* namespace another_rxcpp */
diff --git a/include/another-rxcpp/operators/amb.h b/include/another-rxcpp/operators/amb.h
index 0f84aec..b43ffdc 100644
--- a/include/another-rxcpp/operators/amb.h
+++ b/include/another-rxcpp/operators/amb.h
@@ -15,7 +15,7 @@ namespace amb_internal {
   template <typename T, typename OB>
   auto amb(scheduler::creator_fn sccr, std::vector<observable<T>>& arr, OB ob) noexcept {
     arr.push_back(ob);
-    return [sccr, arr = internal::to_shared(std::move(arr))](auto src) {
+    return [sccr, arr = std::make_shared<std::vector<observable<T>>>(std::move(arr))](auto src) {
       arr->push_back(src);
       return observable<>::create<T>([sccr, arr](subscriber<T> s) {
         auto sctl = internal::stream_controller<T>(s);
diff --git a/include/another-rxcpp/operators/merge.h b/include/another-rxcpp/operators/merge.h
index a72e3b6..eea1041 100644
--- a/include/another-rxcpp/operators/merge.h
+++ b/include/another-rxcpp/operators/merge.h
@@ -15,7 +15,7 @@ namespace merge_internal {
   template <typename T, typename OB>
   auto merge(scheduler::creator_fn sccr, std::vector<observable<T>>& arr, OB ob) noexcept {
     arr.push_back(ob);
-    return [sccr,  arr = internal::to_shared(std::move(arr))](auto src) {
+    return [sccr,  arr = std::make_shared<std::vector<observable<T>>>(std::move(arr))](auto src) {
       arr->push_back(src);
       return observable<>::create<T>([sccr, arr](subscriber<T> s) {
         auto sctl = internal::stream_controller<T>(s);
diff --git a/include/another-rxcpp/subscriber.h b/include/another-rxcpp/subscriber.h
index de2fb1e..f9f730a 100644
--- a/include/another-rxcpp/subscriber.h
+++ b/include/another-rxcpp/subscriber.h
@@ -1,9 +1,6 @@
 #if !defined(__another_rxcpp_h_subscriber__)
 #define __another_rxcpp_h_subscriber__
 
-#include <functional>
-#include <memory>
-#include <optional>
 #include "observer.h"
 
 namespace another_rxcpp {
diff --git a/include/another-rxcpp/subscription.h b/include/another-rxcpp/subscription.h
index 81a2736..420b1cb 100644
--- a/include/another-rxcpp/subscription.h
+++ b/include/another-rxcpp/subscription.h
@@ -10,27 +10,25 @@ class subscription {
   struct member {
     const internal::fn<void()> unsubscribe_;
     const internal::fn<bool()> is_subscribed_;
+    template <typename Unsb, typename Issb>
+      member(Unsb&& unsb, Issb&& issb) noexcept :
+        unsubscribe_(std::forward<Unsb>(unsb)),
+        is_subscribed_(std::forward<Issb>(issb)) {}
   };
 
   std::shared_ptr<member> m_;
 
 public:
-  subscription() = default;
-  subscription(
-    const internal::fn<void()>& unsubscribe,
-    const internal::fn<bool()>& is_subscribed
-  ) noexcept : m_(std::make_shared<member>(member{
-    .unsubscribe_   = unsubscribe,
-    .is_subscribed_ = is_subscribed
-  })) {}
-  subscription(
-    internal::fn<void()>&& unsubscribe,
-    internal::fn<bool()>&& is_subscribed
-  ) noexcept : m_(std::make_shared<member>(member{
-    .unsubscribe_   = std::move(unsubscribe),
-    .is_subscribed_ = std::move(is_subscribed)
-  })) {}
-  subscription(const subscription& src): m_(src.m_){}
+  subscription() noexcept = default;
+  
+  template <typename Unsb, typename Issb>
+    subscription(Unsb&& unsb, Issb&& issb) noexcept :
+      m_(std::make_shared<member>(
+        std::forward<Unsb>(unsb),
+        std::forward<Issb>(issb)
+      )){}
+
+  subscription(const subscription& src) noexcept : m_(src.m_){}
 
   const subscription& operator = (const subscription& src) {
     m_ = src.m_;