diff --git a/src/ctx.cpp b/src/ctx.cpp
index 69dd8c22..c7ffb47d 100644
--- a/src/ctx.cpp
+++ b/src/ctx.cpp
@@ -137,8 +137,8 @@ int zmq::ctx_t::terminate ()
 
     // Connect up any pending inproc connections, otherwise we will hang
     pending_connections_t copy = _pending_connections;
-    for (pending_connections_t::iterator p = copy.begin (); p != copy.end ();
-         ++p) {
+    for (pending_connections_t::iterator p = copy.begin (), end = copy.end ();
+         p != end; ++p) {
         zmq::socket_base_t *s = create_socket (ZMQ_PAIR);
         // create_socket might fail eg: out of memory/sockets limit reached
         zmq_assert (s);
@@ -528,8 +528,9 @@ void zmq::ctx_t::unregister_endpoints (socket_base_t *socket_)
 {
     scoped_lock_t locker (_endpoints_sync);
 
-    for (endpoints_t::iterator it = _endpoints.begin ();
-         it != _endpoints.end ();) {
+    for (endpoints_t::iterator it = _endpoints.begin (),
+                               end = _endpoints.end ();
+         it != end;) {
         if (it->second.socket == socket_)
 #if __cplusplus >= 201103L
             it = _endpoints.erase (it);
diff --git a/src/dish.cpp b/src/dish.cpp
index 4d6ea976..5a7b67a4 100644
--- a/src/dish.cpp
+++ b/src/dish.cpp
@@ -100,16 +100,12 @@ int zmq::dish_t::xjoin (const char *group_)
         return -1;
     }
 
-    subscriptions_t::iterator it = _subscriptions.find (group);
-
     //  User cannot join same group twice
-    if (it != _subscriptions.end ()) {
+    if (!_subscriptions.insert (group).second) {
         errno = EINVAL;
         return -1;
     }
 
-    _subscriptions.insert (group);
-
     msg_t msg;
     int rc = msg.init_join ();
     errno_assert (rc == 0);
@@ -230,8 +226,9 @@ const zmq::blob_t &zmq::dish_t::get_credential () const
 
 void zmq::dish_t::send_subscriptions (pipe_t *pipe_)
 {
-    for (subscriptions_t::iterator it = _subscriptions.begin ();
-         it != _subscriptions.end (); ++it) {
+    for (subscriptions_t::iterator it = _subscriptions.begin (),
+                                   end = _subscriptions.end ();
+         it != end; ++it) {
         msg_t msg;
         int rc = msg.init_join ();
         errno_assert (rc == 0);
diff --git a/src/epoll.cpp b/src/epoll.cpp
index 050783bf..86634c07 100644
--- a/src/epoll.cpp
+++ b/src/epoll.cpp
@@ -75,8 +75,8 @@ zmq::epoll_t::~epoll_t ()
 #else
     close (_epoll_fd);
 #endif
-    for (retired_t::iterator it = _retired.begin (); it != _retired.end ();
-         ++it) {
+    for (retired_t::iterator it = _retired.begin (), end = _retired.end ();
+         it != end; ++it) {
         LIBZMQ_DELETE (*it);
     }
 }
@@ -207,8 +207,8 @@ void zmq::epoll_t::loop ()
         }
 
         //  Destroy retired event sources.
-        for (retired_t::iterator it = _retired.begin (); it != _retired.end ();
-             ++it) {
+        for (retired_t::iterator it = _retired.begin (), end = _retired.end ();
+             it != end; ++it) {
             LIBZMQ_DELETE (*it);
         }
         _retired.clear ();
diff --git a/src/mailbox_safe.cpp b/src/mailbox_safe.cpp
index 624e8543..509aa85a 100644
--- a/src/mailbox_safe.cpp
+++ b/src/mailbox_safe.cpp
@@ -61,10 +61,11 @@ void zmq::mailbox_safe_t::add_signaler (signaler_t *signaler_)
 void zmq::mailbox_safe_t::remove_signaler (signaler_t *signaler_)
 {
     // TODO: make a copy of array and signal outside the lock
+    const std::vector<zmq::signaler_t *>::iterator end = _signalers.end ();
     std::vector<signaler_t *>::iterator it =
-      std::find (_signalers.begin (), _signalers.end (), signaler_);
+      std::find (_signalers.begin (), end, signaler_);
 
-    if (it != _signalers.end ())
+    if (it != end)
         _signalers.erase (it);
 }
 
@@ -81,8 +82,10 @@ void zmq::mailbox_safe_t::send (const command_t &cmd_)
 
     if (!ok) {
         _cond_var.broadcast ();
-        for (std::vector<signaler_t *>::iterator it = _signalers.begin ();
-             it != _signalers.end (); ++it) {
+
+        for (std::vector<signaler_t *>::iterator it = _signalers.begin (),
+                                                 end = _signalers.end ();
+             it != end; ++it) {
             (*it)->send ();
         }
     }
diff --git a/src/mechanism.cpp b/src/mechanism.cpp
index 53a015fb..ad5959bc 100644
--- a/src/mechanism.cpp
+++ b/src/mechanism.cpp
@@ -178,12 +178,14 @@ size_t zmq::mechanism_t::add_basic_properties (unsigned char *ptr_,
     }
 
 
-    for (std::map<std::string, std::string>::const_iterator it =
-           options.app_metadata.begin ();
-         it != options.app_metadata.end (); ++it)
+    for (std::map<std::string, std::string>::const_iterator
+           it = options.app_metadata.begin (),
+           end = options.app_metadata.end ();
+         it != end; ++it) {
         ptr +=
           add_property (ptr, ptr_capacity_ - (ptr - ptr_), it->first.c_str (),
                         it->second.c_str (), strlen (it->second.c_str ()));
+    }
 
     return ptr - ptr_;
 }
@@ -193,9 +195,10 @@ size_t zmq::mechanism_t::basic_properties_len () const
     const char *socket_type = socket_type_string (options.type);
     size_t meta_len = 0;
 
-    for (std::map<std::string, std::string>::const_iterator it =
-           options.app_metadata.begin ();
-         it != options.app_metadata.end (); ++it) {
+    for (std::map<std::string, std::string>::const_iterator
+           it = options.app_metadata.begin (),
+           end = options.app_metadata.end ();
+         it != end; ++it) {
         meta_len +=
           property_len (it->first.c_str (), strlen (it->second.c_str ()));
     }
diff --git a/src/own.cpp b/src/own.cpp
index e7f3c6cd..7588dd07 100644
--- a/src/own.cpp
+++ b/src/own.cpp
@@ -158,7 +158,8 @@ void zmq::own_t::process_term (int linger_)
     zmq_assert (!_terminating);
 
     //  Send termination request to all owned objects.
-    for (owned_t::iterator it = _owned.begin (); it != _owned.end (); ++it)
+    for (owned_t::iterator it = _owned.begin (), end = _owned.end (); it != end;
+         ++it)
         send_term (*it, linger_);
     register_term_acks (static_cast<int> (_owned.size ()));
     _owned.clear ();
diff --git a/src/pgm_receiver.cpp b/src/pgm_receiver.cpp
index cbbaf16d..b70c21b5 100644
--- a/src/pgm_receiver.cpp
+++ b/src/pgm_receiver.cpp
@@ -86,7 +86,8 @@ void zmq::pgm_receiver_t::plug (io_thread_t *io_thread_,
 void zmq::pgm_receiver_t::unplug ()
 {
     //  Delete decoders.
-    for (peers_t::iterator it = peers.begin (); it != peers.end (); ++it) {
+    for (peers_t::iterator it = peers.begin (), end = peers.end (); it != end;
+         ++it) {
         if (it->second.decoder != NULL) {
             LIBZMQ_DELETE (it->second.decoder);
         }
diff --git a/src/poller_base.cpp b/src/poller_base.cpp
index ebcc6997..803389a8 100644
--- a/src/poller_base.cpp
+++ b/src/poller_base.cpp
@@ -65,7 +65,8 @@ void zmq::poller_base_t::add_timer (int timeout_, i_poll_events *sink_, int id_)
 void zmq::poller_base_t::cancel_timer (i_poll_events *sink_, int id_)
 {
     //  Complexity of this operation is O(n). We assume it is rarely used.
-    for (timers_t::iterator it = _timers.begin (); it != _timers.end (); ++it)
+    for (timers_t::iterator it = _timers.begin (), end = _timers.end ();
+         it != end; ++it)
         if (it->second.sink == sink_ && it->second.id == id_) {
             _timers.erase (it);
             return;
diff --git a/src/radio.cpp b/src/radio.cpp
index e31e0dc2..486732ac 100644
--- a/src/radio.cpp
+++ b/src/radio.cpp
@@ -122,8 +122,9 @@ int zmq::radio_t::xsetsockopt (int option_,
 
 void zmq::radio_t::xpipe_terminated (pipe_t *pipe_)
 {
-    for (subscriptions_t::iterator it = _subscriptions.begin ();
-         it != _subscriptions.end ();) {
+    for (subscriptions_t::iterator it = _subscriptions.begin (),
+                                   end = _subscriptions.end ();
+         it != end;) {
         if (it->second == pipe_) {
 #if __cplusplus >= 201103L
             it = _subscriptions.erase (it);
@@ -135,10 +136,13 @@ void zmq::radio_t::xpipe_terminated (pipe_t *pipe_)
         }
     }
 
-    udp_pipes_t::iterator it =
-      std::find (_udp_pipes.begin (), _udp_pipes.end (), pipe_);
-    if (it != _udp_pipes.end ())
-        _udp_pipes.erase (it);
+    {
+        const udp_pipes_t::iterator end = _udp_pipes.end ();
+        const udp_pipes_t::iterator it =
+          std::find (_udp_pipes.begin (), end, pipe_);
+        if (it != end)
+            _udp_pipes.erase (it);
+    }
 
     _dist.pipe_terminated (pipe_);
 }
@@ -159,8 +163,9 @@ int zmq::radio_t::xsend (msg_t *msg_)
     for (subscriptions_t::iterator it = range.first; it != range.second; ++it)
         _dist.match (it->second);
 
-    for (udp_pipes_t::iterator it = _udp_pipes.begin ();
-         it != _udp_pipes.end (); ++it)
+    for (udp_pipes_t::iterator it = _udp_pipes.begin (),
+                               end = _udp_pipes.end ();
+         it != end; ++it)
         _dist.match (*it);
 
     int rc = -1;
diff --git a/src/router.cpp b/src/router.cpp
index 03d117cd..82f94968 100644
--- a/src/router.cpp
+++ b/src/router.cpp
@@ -165,7 +165,7 @@ void zmq::router_t::xread_activated (pipe_t *pipe_)
     if (it == _anonymous_pipes.end ())
         _fq.activated (pipe_);
     else {
-        bool routing_id_ok = identify_peer (pipe_, false);
+        const bool routing_id_ok = identify_peer (pipe_, false);
         if (routing_id_ok) {
             _anonymous_pipes.erase (it);
             _fq.attach (pipe_);
diff --git a/src/server.cpp b/src/server.cpp
index b8c32b9b..becd4eca 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -86,8 +86,9 @@ void zmq::server_t::xread_activated (pipe_t *pipe_)
 
 void zmq::server_t::xwrite_activated (pipe_t *pipe_)
 {
+    const out_pipes_t::iterator end = _out_pipes.end ();
     out_pipes_t::iterator it;
-    for (it = _out_pipes.begin (); it != _out_pipes.end (); ++it)
+    for (it = _out_pipes.begin (); it != end; ++it)
         if (it->second.pipe == pipe_)
             break;
 
diff --git a/src/socket_base.cpp b/src/socket_base.cpp
index de4c58fc..e5626e9a 100644
--- a/src/socket_base.cpp
+++ b/src/socket_base.cpp
@@ -786,12 +786,11 @@ int zmq::socket_base_t::connect (const char *addr_)
         options.connected = true;
         return 0;
     }
-    bool is_single_connect =
+    const bool is_single_connect =
       (options.type == ZMQ_DEALER || options.type == ZMQ_SUB
        || options.type == ZMQ_PUB || options.type == ZMQ_REQ);
     if (unlikely (is_single_connect)) {
-        const endpoints_t::iterator it = _endpoints.find (addr_);
-        if (it != _endpoints.end ()) {
+        if (0 != _endpoints.count (addr_)) {
             // There is no valid use for multiple connects for SUB-PUB nor
             // DEALER-ROUTER nor REQ-REP. Multiple connects produces
             // nonsensical results.
@@ -1551,8 +1550,8 @@ void zmq::socket_base_t::pipe_terminated (pipe_t *pipe_)
     xpipe_terminated (pipe_);
 
     // Remove pipe from inproc pipes
-    for (inprocs_t::iterator it = _inprocs.begin (); it != _inprocs.end ();
-         ++it)
+    for (inprocs_t::iterator it = _inprocs.begin (), end = _inprocs.end ();
+         it != end; ++it)
         if (it->second == pipe_) {
             _inprocs.erase (it);
             break;
@@ -1790,12 +1789,13 @@ int zmq::routing_socket_base_t::xsetsockopt (int option_,
 
 void zmq::routing_socket_base_t::xwrite_activated (pipe_t *pipe_)
 {
+    const out_pipes_t::iterator end = _out_pipes.end ();
     out_pipes_t::iterator it;
-    for (it = _out_pipes.begin (); it != _out_pipes.end (); ++it)
+    for (it = _out_pipes.begin (); it != end; ++it)
         if (it->second.pipe == pipe_)
             break;
 
-    zmq_assert (it != _out_pipes.end ());
+    zmq_assert (it != end);
     zmq_assert (!it->second.active);
     it->second.active = true;
 }
diff --git a/src/socket_poller.cpp b/src/socket_poller.cpp
index c0258a6d..0b9ebc78 100644
--- a/src/socket_poller.cpp
+++ b/src/socket_poller.cpp
@@ -31,6 +31,7 @@
 #include "socket_poller.hpp"
 #include "err.hpp"
 #include "polling_util.hpp"
+#include "macros.hpp"
 
 #include <limits.h>
 
@@ -59,7 +60,8 @@ zmq::socket_poller_t::~socket_poller_t ()
     //  Mark the socket_poller as dead
     _tag = 0xdeadbeef;
 
-    for (items_t::iterator it = _items.begin (); it != _items.end (); ++it) {
+    for (items_t::iterator it = _items.begin (), end = _items.end (); it != end;
+         ++it) {
         // TODO shouldn't this zmq_assert (it->socket->check_tag ()) instead?
         if (it->socket && it->socket->check_tag ()
             && is_thread_safe (*it->socket)) {
@@ -68,8 +70,7 @@ zmq::socket_poller_t::~socket_poller_t ()
     }
 
     if (_signaler != NULL) {
-        delete _signaler;
-        _signaler = NULL;
+        LIBZMQ_DELETE (_signaler);
     }
 
 #if defined ZMQ_POLL_BASED_ON_POLL
@@ -89,7 +90,8 @@ int zmq::socket_poller_t::add (socket_base_t *socket_,
                                void *user_data_,
                                short events_)
 {
-    for (items_t::iterator it = _items.begin (); it != _items.end (); ++it) {
+    for (items_t::iterator it = _items.begin (), end = _items.end (); it != end;
+         ++it) {
         if (it->socket == socket_) {
             errno = EINVAL;
             return -1;
@@ -138,7 +140,8 @@ int zmq::socket_poller_t::add (socket_base_t *socket_,
 
 int zmq::socket_poller_t::add_fd (fd_t fd_, void *user_data_, short events_)
 {
-    for (items_t::iterator it = _items.begin (); it != _items.end (); ++it) {
+    for (items_t::iterator it = _items.begin (), end = _items.end (); it != end;
+         ++it) {
         if (!it->socket && it->fd == fd_) {
             errno = EINVAL;
             return -1;
@@ -169,14 +172,15 @@ int zmq::socket_poller_t::add_fd (fd_t fd_, void *user_data_, short events_)
 
 int zmq::socket_poller_t::modify (socket_base_t *socket_, short events_)
 {
+    const items_t::iterator end = _items.end ();
     items_t::iterator it;
 
-    for (it = _items.begin (); it != _items.end (); ++it) {
+    for (it = _items.begin (); it != end; ++it) {
         if (it->socket == socket_)
             break;
     }
 
-    if (it == _items.end ()) {
+    if (it == end) {
         errno = EINVAL;
         return -1;
     }
@@ -190,14 +194,15 @@ int zmq::socket_poller_t::modify (socket_base_t *socket_, short events_)
 
 int zmq::socket_poller_t::modify_fd (fd_t fd_, short events_)
 {
+    const items_t::iterator end = _items.end ();
     items_t::iterator it;
 
-    for (it = _items.begin (); it != _items.end (); ++it) {
+    for (it = _items.begin (); it != end; ++it) {
         if (!it->socket && it->fd == fd_)
             break;
     }
 
-    if (it == _items.end ()) {
+    if (it == end) {
         errno = EINVAL;
         return -1;
     }
@@ -211,14 +216,15 @@ int zmq::socket_poller_t::modify_fd (fd_t fd_, short events_)
 
 int zmq::socket_poller_t::remove (socket_base_t *socket_)
 {
+    const items_t::iterator end = _items.end ();
     items_t::iterator it;
 
-    for (it = _items.begin (); it != _items.end (); ++it) {
+    for (it = _items.begin (); it != end; ++it) {
         if (it->socket == socket_)
             break;
     }
 
-    if (it == _items.end ()) {
+    if (it == end) {
         errno = EINVAL;
         return -1;
     }
@@ -235,14 +241,15 @@ int zmq::socket_poller_t::remove (socket_base_t *socket_)
 
 int zmq::socket_poller_t::remove_fd (fd_t fd_)
 {
+    const items_t::iterator end = _items.end ();
     items_t::iterator it;
 
-    for (it = _items.begin (); it != _items.end (); ++it) {
+    for (it = _items.begin (); it != end; ++it) {
         if (!it->socket && it->fd == fd_)
             break;
     }
 
-    if (it == _items.end ()) {
+    if (it == end) {
         errno = EINVAL;
         return -1;
     }
@@ -266,7 +273,8 @@ void zmq::socket_poller_t::rebuild ()
         _pollfds = NULL;
     }
 
-    for (items_t::iterator it = _items.begin (); it != _items.end (); ++it) {
+    for (items_t::iterator it = _items.begin (), end = _items.end (); it != end;
+         ++it) {
         if (it->events) {
             if (it->socket && is_thread_safe (*it->socket)) {
                 if (!_use_signaler) {
@@ -292,7 +300,8 @@ void zmq::socket_poller_t::rebuild ()
         _pollfds[0].events = POLLIN;
     }
 
-    for (items_t::iterator it = _items.begin (); it != _items.end (); ++it) {
+    for (items_t::iterator it = _items.begin (), end = _items.end (); it != end;
+         ++it) {
         if (it->events) {
             if (it->socket) {
                 if (!is_thread_safe (*it->socket)) {
@@ -330,7 +339,8 @@ void zmq::socket_poller_t::rebuild ()
     FD_ZERO (_pollset_out.get ());
     FD_ZERO (_pollset_err.get ());
 
-    for (items_t::iterator it = _items.begin (); it != _items.end (); ++it) {
+    for (items_t::iterator it = _items.begin (), end = _items.end (); it != end;
+         ++it) {
         if (it->socket && is_thread_safe (*it->socket) && it->events) {
             _use_signaler = true;
             FD_SET (_signaler->get_fd (), _pollset_in.get ());
@@ -342,7 +352,8 @@ void zmq::socket_poller_t::rebuild ()
     _max_fd = 0;
 
     //  Build the fd_sets for passing to select ().
-    for (items_t::iterator it = _items.begin (); it != _items.end (); ++it) {
+    for (items_t::iterator it = _items.begin (), end = _items.end (); it != end;
+         ++it) {
         if (it->events) {
             //  If the poll item is a 0MQ socket we are interested in input on the
             //  notification file descriptor retrieved by the ZMQ_FD socket option.
@@ -404,8 +415,8 @@ int zmq::socket_poller_t::check_events (zmq::socket_poller_t::event_t *events_,
 #endif
 {
     int found = 0;
-    for (items_t::iterator it = _items.begin ();
-         it != _items.end () && found < n_events_; ++it) {
+    for (items_t::iterator it = _items.begin (), end = _items.end ();
+         it != end && found < n_events_; ++it) {
         //  The poll item is a 0MQ socket. Retrieve pending events
         //  using the ZMQ_EVENTS socket option.
         if (it->socket) {