patch 7.4.2273
Problem:    getwininfo() and getbufinfo() are inefficient.
Solution:   Do not make a copy of all window/buffer-local options.  Make it
            possible to get them with gettabwinvar() or getbufvar().
diff --git a/src/eval.c b/src/eval.c
index 350173a..a8835b1 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -8470,9 +8470,23 @@
 		  || switch_win(&oldcurwin, &oldtabpage, win, tp, TRUE) == OK)
 #endif
 	{
-	    if (*varname == '&')	/* window-local-option */
+	    if (*varname == '&')
 	    {
-		if (get_option_tv(&varname, rettv, 1) == OK)
+		if (varname[1] == NUL)
+		{
+		    /* get all window-local options in a dict */
+		    dict_T	*opts = get_winbuf_options(FALSE);
+
+		    if (opts != NULL)
+		    {
+			rettv->v_type = VAR_DICT;
+			rettv->vval.v_dict = opts;
+			++opts->dv_refcount;
+			done = TRUE;
+		    }
+		}
+		else if (get_option_tv(&varname, rettv, 1) == OK)
+		    /* window-local-option */
 		    done = TRUE;
 	    }
 	    else