2 files changed, 10 insertions, 5 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 960639af152..ffd706a9a82 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2012-08-21  Paul Eggert  <eggert@cs.ucla.edu>
+
+        * lisp.h (vcopy): Use memcpy rather than our own loop.
+        This fixes a performance regression introduced by the recent
+        addition of vcopy.  This means 'vcopy' will need to be modified
+        for a copying collector, but that's OK.  Also, tighten the
+        checking in the assertion.
+
 2012-08-21  Eli Zaretskii  <eliz@gnu.org>
 
         * w32uniscribe.c (uniscribe_shape): Fix producing gstring
diff --git a/src/lisp.h b/src/lisp.h
index 587e584b091..30bbb65f4fa 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2349,11 +2349,8 @@ gc_aset (Lisp_Object array, ptrdiff_t idx, Lisp_Object val)
 LISP_INLINE void
 vcopy (Lisp_Object v, ptrdiff_t offset, Lisp_Object *args, ptrdiff_t count)
 {
-  ptrdiff_t i;
-
-  eassert (offset + count <= ASIZE (v));
-  for (i = 0; i < count; i++)
-    ASET (v, offset + i, args[i]);
+  eassert (0 <= offset && 0 <= count && offset + count <= ASIZE (v));
+  memcpy (XVECTOR (v)->contents + offset, args, count * sizeof *args);
 }
 
 /* Functions to modify hash tables.  */