diff --git a/harbour/ChangeLog b/harbour/ChangeLog
index b3fb7f0afe..7c01d4c076 100644
--- a/harbour/ChangeLog
+++ b/harbour/ChangeLog
@@ -16,6 +16,22 @@
    The license applies to all entries newer than 2009-04-28.
 */
 
+2011-03-05 15:41 UTC+0100 Przemyslaw Czerpak (druzus/at/priv.onet.pl)
+  * harbour/include/hbexprb.c
+    + enabled o:var += <cString> optimization when -ko switch is used
+      I added this optimization few years ago but I haven't enabled it
+      so far.
+
+  + harbour/tests/speedstr.prg
+    + added test code for <exp> += <cString> optimization
+      Try this code compiled with -kc switch (disabled += optimization)
+      without any -k? switches (default, += optimized for all expressions
+      except <obj>:<msg>) and finally with -ko switch (+= optimized for
+      all expressions)
+      (Warning for larger string non optimized code begins to be _very_
+      slow, i.e. for '#define N_LOOP 1000000' it needs fee minutes to
+      pass single test)
+
 2011-03-04 17:50 UTC-0800 Pritpal Bedi (bedipritpal@hotmail.com)
   * contrib/hbxbp/xbpappevent.prg
     + Added: XbpAppEventToQKeyEvent() and XbpAppEventModifier()
diff --git a/harbour/include/hbexprb.c b/harbour/include/hbexprb.c
index c57c764c23..a6e75e3deb 100644
--- a/harbour/include/hbexprb.c
+++ b/harbour/include/hbexprb.c
@@ -58,9 +58,7 @@
 #endif
 
 #define HB_USE_ARRAYAT_REF
-/* Temporary disabled optimization with references to object variables
-   until we will not have extended reference items in our HVM [druzus] */
-/* #define HB_USE_OBJMSG_REF */
+#define HB_USE_OBJMSG_REF
 
 
 /* Forward declarations
@@ -4804,7 +4802,7 @@ static void hb_compExprPushOperEq( HB_EXPR_PTR pSelf, HB_BYTE bOpEq, HB_COMP_DEC
    if( pSelf->value.asOperator.pLeft->ExprType == HB_ET_SEND )
    {
 #ifdef HB_USE_OBJMSG_REF
-      if( bOpEq != bNewOp )
+      if( HB_SUPPORT_EXTOPT && bOpEq != bNewOp )
       {
          hb_compExprPushSendPop( pSelf->value.asOperator.pLeft, HB_COMP_PARAM );
          HB_GEN_FUNC1( PCode1, HB_P_PUSHOVARREF );
@@ -4953,7 +4951,7 @@ static void hb_compExprUseOperEq( HB_EXPR_PTR pSelf, HB_BYTE bOpEq, HB_COMP_DECL
    if( pSelf->value.asOperator.pLeft->ExprType == HB_ET_SEND )
    {
 #ifdef HB_USE_OBJMSG_REF
-      if( bOpEq != bNewOp )
+      if( HB_SUPPORT_EXTOPT && bOpEq != bNewOp )
       {
          hb_compExprPushSendPop( pSelf->value.asOperator.pLeft, HB_COMP_PARAM );
          HB_GEN_FUNC1( PCode1, HB_P_PUSHOVARREF );
@@ -5072,7 +5070,7 @@ static void hb_compExprPushPreOp( HB_EXPR_PTR pSelf, HB_BYTE bOper, HB_COMP_DECL
    if( pSelf->value.asOperator.pLeft->ExprType == HB_ET_SEND )
    {
 #ifdef HB_USE_OBJMSG_REF
-      if( HB_SUPPORT_HARBOUR )
+      if( HB_SUPPORT_EXTOPT )
       {
          hb_compExprPushSendPop( pSelf->value.asOperator.pLeft, HB_COMP_PARAM );
          HB_GEN_FUNC1( PCode1, HB_P_PUSHOVARREF );
@@ -5174,7 +5172,7 @@ static void hb_compExprPushPostOp( HB_EXPR_PTR pSelf, HB_BYTE bOper, HB_COMP_DEC
    if( pSelf->value.asOperator.pLeft->ExprType == HB_ET_SEND )
    {
 #ifdef HB_USE_OBJMSG_REF
-      if( HB_SUPPORT_HARBOUR )
+      if( HB_SUPPORT_EXTOPT )
       {
          /* push reference to current value */
          hb_compExprPushSendPop( pSelf->value.asOperator.pLeft, HB_COMP_PARAM );
@@ -5285,7 +5283,7 @@ static void hb_compExprUsePreOp( HB_EXPR_PTR pSelf, HB_BYTE bOper, HB_COMP_DECL
    if( pSelf->value.asOperator.pLeft->ExprType == HB_ET_SEND )
    {
 #ifdef HB_USE_OBJMSG_REF
-      if( HB_SUPPORT_HARBOUR )
+      if( HB_SUPPORT_EXTOPT )
       {
          /* push reference to current value */
          hb_compExprPushSendPop( pSelf->value.asOperator.pLeft, HB_COMP_PARAM );
diff --git a/harbour/tests/speedstr.prg b/harbour/tests/speedstr.prg
new file mode 100644
index 0000000000..658367616b
--- /dev/null
+++ b/harbour/tests/speedstr.prg
@@ -0,0 +1,77 @@
+/*
+ * $Id$
+ */
+
+/*
+ * Harbour Project source code:
+ *    speed test program for string concatenation by += operator
+ *
+ * Copyright 2011 Przemyslaw Czerpak <druzus / at / priv.onet.pl>
+ * www - http://harbour-project.org
+ *
+ */
+
+#define N_LOOP 200000
+
+#ifndef __XHARBOUR__
+   #translate secondsCPU( => hb_secondsCPU(
+#endif
+#ifdef __XPP__
+   #translate secondsCPU( => seconds(
+#endif
+#ifdef __HARBOUR__
+#include "hbclass.ch"
+#endif
+
+proc main()
+   memvar p
+   local i, t
+   local l, o
+   static s, s2[1]
+   private p
+   p := s2[1] := s := l := ""
+   t := secondsCPU()
+   for i := 1 to N_LOOP
+      l += chr( i )
+   next
+   t := secondsCPU() - t
+   ? "LOCAL  +=", t, "sec."
+   t := secondsCPU()
+   for i := 1 to N_LOOP
+      s += chr( i )
+   next
+   t := secondsCPU() - t
+   ? "STATIC +=", t, "sec."
+   t := secondsCPU()
+   for i := 1 to N_LOOP
+      s2[1] += chr( i )
+   next
+   t := secondsCPU() - t
+   ? "ARRAY[] +=", t, "sec."
+   t := secondsCPU()
+   for i := 1 to N_LOOP
+      p += chr( i )
+   next
+   t := secondsCPU() - t
+   ? "PRIVATE +=", t, "sec."
+   p := ""; s := "p"
+   t := secondsCPU()
+   for i := 1 to N_LOOP
+      &s += chr( i )
+   next
+   t := secondsCPU() - t
+   ? "MACRO +=", t, "sec."
+   o := mycls():new(); o:v := ""
+   t := secondsCPU()
+   for i := 1 to N_LOOP
+      o:v += chr( i )
+   next
+   t := secondsCPU() - t
+   ? "OBJECT:VAR +=", t, "sec."
+   wait
+return
+
+class mycls
+   exported:
+      var v
+endclass