diff --git a/CHANGELOG b/CHANGELOG
index e926e9a0..3fece96c 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -10,10 +10,6 @@ FUTURE
     (sizeof(int)). In ppp.c an assumption is made on the availability of
     a thread subsystem. Either PPP needs to be moved to contrib/ports/???
     or rearranged to be more generic.
-    
-  * TODO: review the the sequential netconn and socket API (lwip/src/api)
-    for bugs and performance issues. Frequent system calls (e.g. sys_mbox_fetch)
-    slooow things down considerably. 
 
 HISTORY
 
@@ -170,6 +166,12 @@ HISTORY
   * tcp.c: Fixed bug #1895 (tcp_bind not correct) by introducing a list of
     bound but unconnected (and non-listening) tcp_pcbs.
 
+  2007-05-22 Frédéric Bernon
+  * sys.h, sys.c, api_lib.c, tcpip.c: remove sys_mbox_fetch_timeout() (was only
+    used for LWIP_SO_RCVTIMEO option) and use sys_arch_mbox_fetch() instead of
+    sys_mbox_fetch() in api files. Now, users SHOULD NOT use internal lwIP features
+    like "sys_timeout" in their application threads.
+
   2007-05-22 Frédéric Bernon
   * api.h, api_lib.c, api_msg.h, api_msg.c: change the struct api_msg_msg to see
     which parameters are used by which do_xxx function, and to avoid "misusing"
diff --git a/src/api/api_lib.c b/src/api/api_lib.c
index 06bcc8df..df3e5cbb 100644
--- a/src/api/api_lib.c
+++ b/src/api/api_lib.c
@@ -443,7 +443,7 @@ netconn_accept(struct netconn *conn)
     return NULL;
   }
   
-  sys_mbox_fetch(conn->acceptmbox, (void *)&newconn);
+  sys_arch_mbox_fetch(conn->acceptmbox, (void *)&newconn, 0);
   /* Register event with callback */
   if (conn->callback)
       (*conn->callback)(conn, NETCONN_EVT_RCVMINUS, 0);
@@ -488,7 +488,7 @@ netconn_recv(struct netconn *conn)
       return NULL;
     }
     
-    sys_mbox_fetch(conn->recvmbox, (void *)&p);
+    sys_arch_mbox_fetch(conn->recvmbox, (void *)&p, 0);
 
     if (p != NULL)
     {
@@ -529,9 +529,9 @@ netconn_recv(struct netconn *conn)
   } else {
 #if (LWIP_UDP || LWIP_RAW)
 #if LWIP_SO_RCVTIMEO
-    sys_mbox_fetch_timeout(conn->recvmbox, (void *)&buf, conn->recv_timeout);
+    sys_arch_mbox_fetch(conn->recvmbox, (void *)&buf, conn->recv_timeout);
 #else
-    sys_mbox_fetch(conn->recvmbox, (void *)&buf);
+    sys_arch_mbox_fetch(conn->recvmbox, (void *)&buf, 0);
 #endif /* LWIP_SO_RCVTIMEO*/
     if (buf!=NULL)
      { conn->recv_avail -= buf->p->tot_len;
diff --git a/src/api/tcpip.c b/src/api/tcpip.c
index d0f07fbf..fd107a36 100644
--- a/src/api/tcpip.c
+++ b/src/api/tcpip.c
@@ -321,7 +321,7 @@ tcpip_apimsg(struct api_msg *apimsg)
     msg.type = TCPIP_MSG_API;
     msg.msg.apimsg = apimsg;
     sys_mbox_post(mbox, &msg);
-    sys_mbox_fetch(apimsg->msg.conn->mbox, NULL);
+    sys_arch_mbox_fetch(apimsg->msg.conn->mbox, NULL, 0);
     return ERR_OK;
   }
   return ERR_VAL;
@@ -333,17 +333,17 @@ err_t tcpip_netifapi(struct netifapi_msg* netifapimsg)
   struct tcpip_msg msg;
   
   if (mbox != SYS_MBOX_NULL) {
-    netifapimsg->sem = sys_sem_new(0);      
+    netifapimsg->sem = sys_sem_new(0);
     if (netifapimsg->sem == SYS_SEM_NULL) {
       netifapimsg->err = ERR_MEM;
       return netifapimsg->err;
-    }  
-      
+    }
+    
     msg.type = TCPIP_MSG_NETIFAPI;
     msg.msg.netifapimsg = netifapimsg;
     sys_mbox_post(mbox, &msg);
     sys_sem_wait(netifapimsg->sem);
-    sys_sem_free(netifapimsg->sem);    
+    sys_sem_free(netifapimsg->sem);
     return netifapimsg->err;
   }
   return ERR_VAL;
diff --git a/src/core/sys.c b/src/core/sys.c
index 26d754ec..a4b7d8d1 100644
--- a/src/core/sys.c
+++ b/src/core/sys.c
@@ -44,11 +44,8 @@ struct sswt_cb
 };
 
 
-#if LWIP_SO_RCVTIMEO
-void sys_mbox_fetch_timeout(sys_mbox_t mbox, void **msg, u32_t timeout)
-#else
-void sys_mbox_fetch(sys_mbox_t mbox, void **msg)
-#endif /* LWIP_SO_RCVTIMEO */
+void
+sys_mbox_fetch(sys_mbox_t mbox, void **msg)
 {
   u32_t time;
   struct sys_timeouts *timeouts;
@@ -60,38 +57,15 @@ void sys_mbox_fetch(sys_mbox_t mbox, void **msg)
   timeouts = sys_arch_timeouts();
 
   if (!timeouts || !timeouts->next) {
-#if LWIP_SO_RCVTIMEO  
-    time = sys_arch_mbox_fetch(mbox, msg, timeout);
-#else
     time = sys_arch_mbox_fetch(mbox, msg, 0);
-#endif /* LWIP_SO_RCVTIMEO */
   } else {
     if (timeouts->next->time > 0) {
-#if LWIP_SO_RCVTIMEO  
-      time = sys_arch_mbox_fetch(mbox, msg, (timeout?((timeout<timeouts->next->time)?timeout:timeouts->next->time):timeouts->next->time));
-#else
       time = sys_arch_mbox_fetch(mbox, msg, timeouts->next->time);
-#endif /* LWIP_SO_RCVTIMEO */
     } else {
       time = SYS_ARCH_TIMEOUT;
     }
 
     if (time == SYS_ARCH_TIMEOUT) {
-#if LWIP_SO_RCVTIMEO  
-      if ((timeout) && (timeout<timeouts->next->time)) {        
-      /* If time == SYS_ARCH_TIMEOUT, and we have wait "fetch's timeout" and not "timer's timeout",
-         The timeout variable is the number of milliseconds we have waited for the message. */
-        timeouts->next->time -= timeout;
-      } else {
-      /* The timeouts->next->time variable is the number of milliseconds we have waited for the message.  */
-        if (timeouts->next->time < timeout) {
-          timeout -= timeouts->next->time;
-        } else {
-          /* either timeout == 0, or timeout must == timeouts->next->time */
-          if (timeout) timeout = SYS_ARCH_TIMEOUT;
-        }
-#endif /* LWIP_SO_RCVTIMEO */
-
       /* If time == SYS_ARCH_TIMEOUT, a timeout occured before a message
          could be fetched. We should now call the timeout handler and
          deallocate the memory allocated for the timeout. */
@@ -104,16 +78,9 @@ void sys_mbox_fetch(sys_mbox_t mbox, void **msg)
         LWIP_DEBUGF(SYS_DEBUG, ("smf calling h=%p(%p)\n", (void *)h, (void *)arg));
         h(arg);
       }
-      
-#if LWIP_SO_RCVTIMEO  
-      if (timeout != SYS_ARCH_TIMEOUT)
-#endif /* LWIP_SO_RCVTIMEO */
-      
+
       /* We try again to fetch a message from the mbox. */
       goto again;
-#if LWIP_SO_RCVTIMEO  
-      }
-#endif /* LWIP_SO_RCVTIMEO */
     } else {
       /* If time != SYS_ARCH_TIMEOUT, a message was received before the timeout
          occured. The time variable is set to the number of
@@ -124,14 +91,7 @@ void sys_mbox_fetch(sys_mbox_t mbox, void **msg)
         timeouts->next->time = 0;
       }
     }
-
   }
-  
-#if LWIP_SO_RCVTIMEO
-  if ((time == SYS_ARCH_TIMEOUT) && (msg))
-   { (*msg)=NULL;
-   }
-#endif /* LWIP_SO_RCVTIMEO */
 }
 
 void
diff --git a/src/include/lwip/sys.h b/src/include/lwip/sys.h
index c6cd14e2..0a2d3fc4 100644
--- a/src/include/lwip/sys.h
+++ b/src/include/lwip/sys.h
@@ -58,7 +58,6 @@ struct sys_timeo {u8_t dummy;};
 #define sys_arch_sem_wait(s,t)
 #define sys_sem_free(s)
 #define sys_mbox_new() 0
-#define sys_mbox_fetch_timeout(m,d,t)
 #define sys_mbox_fetch(m,d)
 #define sys_mbox_post(m,d)
 #define sys_mbox_free(m)
@@ -132,12 +131,7 @@ u32_t sys_arch_mbox_tryfetch(sys_mbox_t mbox, void **msg);
 /* For now, we map straight to sys_arch implementation. */
 #define sys_mbox_tryfetch(mbox, msg) sys_arch_mbox_tryfetch(mbox, msg)
 void sys_mbox_free(sys_mbox_t mbox);
-#if LWIP_SO_RCVTIMEO
-void sys_mbox_fetch_timeout(sys_mbox_t mbox, void **msg, u32_t timeout);
-#define sys_mbox_fetch(m,d) sys_mbox_fetch_timeout(m,d,0)
-#else
 void sys_mbox_fetch(sys_mbox_t mbox, void **msg);
-#endif /* LWIP_SO_RCVTIMEO */
 
 /* Thread functions. */
 sys_thread_t sys_thread_new(void (* thread)(void *arg), void *arg, int prio);