Create less garbage to collect while reading symbols.

* src/lread.c (read1): When interning a symbol, only create a new
string object for the name if we're going to use it for a new symbol
object.

src/lread.c

@@ -3442,18 +3442,43 @@ read1 (Lisp_Object readcharfun, int *pch, bool first_in_list)
 	    if (! NILP (result))
 	      return unbind_to (count, result);
 	  }
-
+	{
+	  Lisp_Object result;
 	  ptrdiff_t nbytes = p - read_buffer;
 	  ptrdiff_t nchars
 	    = (multibyte
 	       ? multibyte_chars_in_text ((unsigned char *) read_buffer,
 					  nbytes)
 	       : nbytes);
-	Lisp_Object name = ((uninterned_symbol && ! NILP (Vpurify_flag)
+
+	  if (uninterned_symbol)
+	    {
+	      Lisp_Object name
+		= ((! NILP (Vpurify_flag)
 		    ? make_pure_string : make_specified_string)
 		   (read_buffer, nchars, nbytes, multibyte));
-	Lisp_Object result = (uninterned_symbol ? Fmake_symbol (name)
-			      : Fintern (name, Qnil));
+	      result = Fmake_symbol (name);
+	    }
+	  else
+	    {
+	      /* Don't create the string object for the name unless
+		 we're going to retain it in a new symbol.
+
+		 Like intern_1 but supports multibyte names.  */
+	      Lisp_Object obarray = check_obarray (Vobarray);
+	      Lisp_Object tem = oblookup (obarray, read_buffer,
+					  nchars, nbytes);
+
+	      if (SYMBOLP (tem))
+		result = tem;
+	      else
+		{
+		  Lisp_Object name
+		    = make_specified_string (read_buffer, nchars, nbytes,
+					     multibyte);
+		  result = intern_driver (name, obarray, tem);
+		}
+	    }
 
 	  if (EQ (Vread_with_symbol_positions, Qt)
 	      || EQ (Vread_with_symbol_positions, readcharfun))
@@ -3463,6 +3488,7 @@ read1 (Lisp_Object readcharfun, int *pch, bool first_in_list)
 	  return unbind_to (count, result);
 	}
       }
+    }
 }