1 files changed, 8 insertions, 1 deletions
diff --git a/pp_hot.c b/pp_hot.c
index b52563a38f..f7183a8f12 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -1459,7 +1459,14 @@ PP(pp_iter)
 	/* integer increment */
 	if (cx->blk_loop.iterix > cx->blk_loop.itermax)
 	    RETPUSHNO;
-	sv_setiv(*cx->blk_loop.itervar, cx->blk_loop.iterix++);
+
+	/* we know that the loop index SV is IV capable, so we can save
+	 * some time by doing the essential work of sv_setiv() ourself.
+	 */
+	sv = *cx->blk_loop.itervar;
+	(void)SvIOK_only(sv);
+	SvIVX(sv) = cx->blk_loop.iterix++;
+
 	RETPUSHYES;
     }