diff --git a/mandel.s b/mandel.s
index 787243f..39e71b0 100644
--- a/mandel.s
+++ b/mandel.s
@@ -262,7 +262,10 @@ palette_chroma_entries = 15
 
 .code
 
-z_buffer_len = 16
+;z_buffer_len = 16 ; 10.863 ms/px
+;z_buffer_len = 12 ; 10.619 ms/px
+z_buffer_len = 8 ; 10.612 ms/px
+;z_buffer_len = 4 ; 12.395 ms/px
 z_buffer_mask = z_buffer_len - 1
 z_buffer:
     ; the last N zx/zy values