diff --git a/ldo.c b/ldo.c
index 155ecf76..0606b59d 100644
--- a/ldo.c
+++ b/ldo.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ldo.c,v 2.138 2015/05/22 17:48:19 roberto Exp roberto $
+** $Id: ldo.c,v 2.139 2015/06/18 14:19:52 roberto Exp roberto $
 ** Stack and Call structure of Lua
 ** See Copyright Notice in lua.h
 */
@@ -684,7 +684,7 @@ static void f_parser (lua_State *L, void *ud) {
   int c = zgetc(p->z);  /* read first character */
   if (c == LUA_SIGNATURE[0]) {
     checkmode(L, p->mode, "binary");
-    cl = luaU_undump(L, p->z, &p->buff, p->name);
+    cl = luaU_undump(L, p->z, p->name);
   }
   else {
     checkmode(L, p->mode, "text");
diff --git a/lgc.c b/lgc.c
index 22d36aed..924445fa 100644
--- a/lgc.c
+++ b/lgc.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.c,v 2.205 2015/03/25 13:42:19 roberto Exp roberto $
+** $Id: lgc.c,v 2.206 2015/07/13 13:30:03 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -769,12 +769,11 @@ static GCObject **sweeptolive (lua_State *L, GCObject **p, int *n) {
 */
 
 /*
-** If possible, free concatenation buffer and shrink string table
+** If possible, shrink string table
 */
 static void checkSizes (lua_State *L, global_State *g) {
   if (g->gckind != KGC_EMERGENCY) {
     l_mem olddebt = g->GCdebt;
-    luaZ_freebuffer(L, &g->buff);  /* free concatenation buffer */
     if (g->strt.nuse < g->strt.size / 4)  /* string table too big? */
       luaS_resize(L, g->strt.size / 2);  /* shrink it a little */
     g->GCestimate += g->GCdebt - olddebt;  /* update estimate */
diff --git a/lstate.c b/lstate.c
index d1679aaf..576485dc 100644
--- a/lstate.c
+++ b/lstate.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.c,v 2.128 2015/03/04 13:31:21 roberto Exp roberto $
+** $Id: lstate.c,v 2.129 2015/07/13 13:30:03 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -241,7 +241,6 @@ static void close_state (lua_State *L) {
   if (g->version)  /* closing a fully built state? */
     luai_userstateclose(L);
   luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
-  luaZ_freebuffer(L, &g->buff);
   freestack(L);
   lua_assert(gettotalbytes(g) == sizeof(LG));
   (*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0);  /* free main block */
@@ -310,7 +309,6 @@ LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
   g->strt.size = g->strt.nuse = 0;
   g->strt.hash = NULL;
   setnilvalue(&g->l_registry);
-  luaZ_initbuffer(L, &g->buff);
   g->panic = NULL;
   g->version = NULL;
   g->gcstate = GCSpause;
diff --git a/lstate.h b/lstate.h
index aad379fd..61dd99f9 100644
--- a/lstate.h
+++ b/lstate.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.h,v 2.122 2015/06/01 16:34:37 roberto Exp roberto $
+** $Id: lstate.h,v 2.123 2015/07/04 16:33:17 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -131,7 +131,6 @@ typedef struct global_State {
   GCObject *tobefnz;  /* list of userdata to be GC */
   GCObject *fixedgc;  /* list of objects not to be collected */
   struct lua_State *twups;  /* list of threads with open upvalues */
-  Mbuffer buff;  /* temporary buffer for string concatenation */
   unsigned int gcfinnum;  /* number of finalizers to call in each GC step */
   int gcpause;  /* size of pause between successive GCs */
   int gcstepmul;  /* GC 'granularity' */
diff --git a/lstring.c b/lstring.c
index c53325d0..588ee546 100644
--- a/lstring.c
+++ b/lstring.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lstring.c,v 2.49 2015/06/01 16:34:37 roberto Exp roberto $
+** $Id: lstring.c,v 2.50 2015/06/18 14:20:32 roberto Exp roberto $
 ** String table (keeps all strings handled by Lua)
 ** See Copyright Notice in lua.h
 */
@@ -119,8 +119,7 @@ void luaS_init (lua_State *L) {
 /*
 ** creates a new string object
 */
-static TString *createstrobj (lua_State *L, const char *str, size_t l,
-                              int tag, unsigned int h) {
+static TString *createstrobj (lua_State *L, size_t l, int tag, unsigned int h) {
   TString *ts;
   GCObject *o;
   size_t totalsize;  /* total size of TString object */
@@ -129,12 +128,18 @@ static TString *createstrobj (lua_State *L, const char *str, size_t l,
   ts = gco2ts(o);
   ts->hash = h;
   ts->extra = 0;
-  memcpy(getaddrstr(ts), str, l * sizeof(char));
   getaddrstr(ts)[l] = '\0';  /* ending 0 */
   return ts;
 }
 
 
+TString *luaS_createlngstrobj (lua_State *L, size_t l) {
+  TString *ts = createstrobj(L, l, LUA_TLNGSTR, G(L)->seed);
+  ts->u.lnglen = l;
+  return ts;
+}
+
+
 void luaS_remove (lua_State *L, TString *ts) {
   stringtable *tb = &G(L)->strt;
   TString **p = &tb->hash[lmod(ts->hash, tb->size)];
@@ -166,7 +171,8 @@ static TString *internshrstr (lua_State *L, const char *str, size_t l) {
     luaS_resize(L, g->strt.size * 2);
     list = &g->strt.hash[lmod(h, g->strt.size)];  /* recompute with new size */
   }
-  ts = createstrobj(L, str, l, LUA_TSHRSTR, h);
+  ts = createstrobj(L, l, LUA_TSHRSTR, h);
+  memcpy(getaddrstr(ts), str, l * sizeof(char));
   ts->shrlen = cast_byte(l);
   ts->u.hnext = *list;
   *list = ts;
@@ -185,8 +191,8 @@ TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
     TString *ts;
     if (l >= (MAX_SIZE - sizeof(TString))/sizeof(char))
       luaM_toobig(L);
-    ts = createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed);
-    ts->u.lnglen = l;
+    ts = luaS_createlngstrobj(L, l);
+    memcpy(getaddrstr(ts), str, l * sizeof(char));
     return ts;
   }
 }
diff --git a/lstring.h b/lstring.h
index cba3cb28..0d8e089c 100644
--- a/lstring.h
+++ b/lstring.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lstring.h,v 1.58 2015/03/04 13:31:21 roberto Exp roberto $
+** $Id: lstring.h,v 1.59 2015/03/25 13:42:19 roberto Exp roberto $
 ** String table (keep all strings handled by Lua)
 ** See Copyright Notice in lua.h
 */
@@ -42,6 +42,7 @@ LUAI_FUNC void luaS_remove (lua_State *L, TString *ts);
 LUAI_FUNC Udata *luaS_newudata (lua_State *L, size_t s);
 LUAI_FUNC TString *luaS_newlstr (lua_State *L, const char *str, size_t l);
 LUAI_FUNC TString *luaS_new (lua_State *L, const char *str);
+LUAI_FUNC TString *luaS_createlngstrobj (lua_State *L, size_t l);
 
 
 #endif
diff --git a/lundump.c b/lundump.c
index 039e4a0f..50c9f0fe 100644
--- a/lundump.c
+++ b/lundump.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lundump.c,v 2.40 2014/06/19 18:27:20 roberto Exp roberto $
+** $Id: lundump.c,v 2.41 2014/11/02 19:19:04 roberto Exp roberto $
 ** load precompiled Lua chunks
 ** See Copyright Notice in lua.h
 */
@@ -32,7 +32,6 @@
 typedef struct {
   lua_State *L;
   ZIO *Z;
-  Mbuffer *b;
   const char *name;
 } LoadState;
 
@@ -92,10 +91,15 @@ static TString *LoadString (LoadState *S) {
     LoadVar(S, size);
   if (size == 0)
     return NULL;
-  else {
-    char *s = luaZ_openspace(S->L, S->b, --size);
-    LoadVector(S, s, size);
-    return luaS_newlstr(S->L, s, size);
+  else if (--size <= LUAI_MAXSHORTLEN) {  /* short string? */
+    char buff[LUAI_MAXSHORTLEN];
+    LoadVector(S, buff, size);
+    return luaS_newlstr(S->L, buff, size);
+  }
+  else {  /* long string */
+    TString *ts = luaS_createlngstrobj(S->L, size);
+    LoadVector(S, getaddrstr(ts), size);  /* load directly in final place */
+    return ts;
   }
 }
 
@@ -251,8 +255,7 @@ static void checkHeader (LoadState *S) {
 /*
 ** load precompiled chunk
 */
-LClosure *luaU_undump(lua_State *L, ZIO *Z, Mbuffer *buff,
-                      const char *name) {
+LClosure *luaU_undump(lua_State *L, ZIO *Z, const char *name) {
   LoadState S;
   LClosure *cl;
   if (*name == '@' || *name == '=')
@@ -263,7 +266,6 @@ LClosure *luaU_undump(lua_State *L, ZIO *Z, Mbuffer *buff,
     S.name = name;
   S.L = L;
   S.Z = Z;
-  S.b = buff;
   checkHeader(&S);
   cl = luaF_newLclosure(L, LoadByte(&S));
   setclLvalue(L, L->top, cl);
diff --git a/lundump.h b/lundump.h
index 45194532..bc9f99a2 100644
--- a/lundump.h
+++ b/lundump.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lundump.h,v 1.43 2014/04/15 14:28:20 roberto Exp roberto $
+** $Id: lundump.h,v 1.44 2014/06/19 18:27:20 roberto Exp roberto $
 ** load precompiled Lua chunks
 ** See Copyright Notice in lua.h
 */
@@ -23,8 +23,7 @@
 #define LUAC_FORMAT	0	/* this is the official format */
 
 /* load one chunk; from lundump.c */
-LUAI_FUNC LClosure* luaU_undump (lua_State* L, ZIO* Z, Mbuffer* buff,
-                                 const char* name);
+LUAI_FUNC LClosure* luaU_undump (lua_State* L, ZIO* Z, const char* name);
 
 /* dump one chunk; from ldump.c */
 LUAI_FUNC int luaU_dump (lua_State* L, const Proto* f, lua_Writer w,
diff --git a/lvm.c b/lvm.c
index 6a6710b3..59f36e3a 100644
--- a/lvm.c
+++ b/lvm.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.c,v 2.249 2015/08/03 19:50:49 roberto Exp roberto $
+** $Id: lvm.c,v 2.250 2015/08/03 20:40:26 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -445,6 +445,17 @@ int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2) {
 
 #define isemptystr(o)	(ttisshrstring(o) && tsvalue(o)->shrlen == 0)
 
+/* copy strings in stack from top - n up to top - 1 to buffer */
+static void copy2buff (StkId top, int n, char *buff) {
+  size_t tl = 0;  /* size already copied */
+  do {
+    size_t l = vslen(top - n);  /* length of string being copied */
+    memcpy(buff + tl, svalue(top - n), l * sizeof(char));
+    tl += l;
+  } while (--n > 0);
+}
+
+
 /*
 ** Main operation for concatenation: concat 'total' values in the stack,
 ** from 'L->top - total' up to 'L->top - 1'.
@@ -464,24 +475,24 @@ void luaV_concat (lua_State *L, int total) {
     else {
       /* at least two non-empty string values; get as many as possible */
       size_t tl = vslen(top - 1);
-      char *buffer;
-      int i;
-      /* collect total length */
-      for (i = 1; i < total && tostring(L, top-i-1); i++) {
-        size_t l = vslen(top - i - 1);
+      TString *ts;
+      /* collect total length and number of strings */
+      for (n = 1; n < total && tostring(L, top - n - 1); n++) {
+        size_t l = vslen(top - n - 1);
         if (l >= (MAX_SIZE/sizeof(char)) - tl)
           luaG_runerror(L, "string length overflow");
         tl += l;
       }
-      buffer = luaZ_openspace(L, &G(L)->buff, tl);
-      tl = 0;
-      n = i;
-      do {  /* copy all strings to buffer */
-        size_t l = vslen(top - i);
-        memcpy(buffer+tl, svalue(top-i), l * sizeof(char));
-        tl += l;
-      } while (--i > 0);
-      setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));  /* create result */
+      if (tl <= LUAI_MAXSHORTLEN) {  /* is result a short string? */
+        char buff[LUAI_MAXSHORTLEN];
+        copy2buff(top, n, buff);  /* copy strings to buffer */
+        ts = luaS_newlstr(L, buff, tl);
+      }
+      else {  /* long string; copy strings directly to final result */
+        ts = luaS_createlngstrobj(L, tl);
+        copy2buff(top, n, getaddrstr(ts));
+      }
+      setsvalue2s(L, top - n, ts);  /* create result */
     }
     total -= n-1;  /* got 'n' strings to create 1 new */
     L->top -= n-1;  /* popped 'n' strings and pushed one */
diff --git a/lzio.c b/lzio.c
index 63ade652..eb6151a0 100644
--- a/lzio.c
+++ b/lzio.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lzio.c,v 1.35 2012/05/14 13:34:18 roberto Exp roberto $
+** $Id: lzio.c,v 1.36 2014/11/02 19:19:04 roberto Exp roberto $
 ** Buffered streams
 ** See Copyright Notice in lua.h
 */
@@ -66,13 +66,3 @@ size_t luaZ_read (ZIO *z, void *b, size_t n) {
   return 0;
 }
 
-/* ------------------------------------------------------------------------ */
-char *luaZ_openspace (lua_State *L, Mbuffer *buff, size_t n) {
-  if (n > buff->buffsize) {
-    if (n < LUA_MINBUFFER) n = LUA_MINBUFFER;
-    luaZ_resizebuffer(L, buff, n);
-  }
-  return buff->buffer;
-}
-
-
diff --git a/lzio.h b/lzio.h
index 8a0c8171..fb310b99 100644
--- a/lzio.h
+++ b/lzio.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lzio.h,v 1.29 2014/12/19 13:45:40 roberto Exp roberto $
+** $Id: lzio.h,v 1.30 2014/12/19 17:26:14 roberto Exp roberto $
 ** Buffered streams
 ** See Copyright Notice in lua.h
 */
@@ -44,7 +44,6 @@ typedef struct Mbuffer {
 #define luaZ_freebuffer(L, buff)	luaZ_resizebuffer(L, buff, 0)
 
 
-LUAI_FUNC char *luaZ_openspace (lua_State *L, Mbuffer *buff, size_t n);
 LUAI_FUNC void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader,
                                         void *data);
 LUAI_FUNC size_t luaZ_read (ZIO* z, void *b, size_t n);	/* read next n bytes */