From 404f1a29525f18f33dc5d55e447218f158e2ad7c Mon Sep 17 00:00:00 2001
From: Go101 <22589241+go101@users.noreply.github.com>
Date: Mon, 24 May 2021 08:46:11 -0400
Subject: [PATCH] Updated SliceTricks (markdown)

---
 SliceTricks.md | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/SliceTricks.md b/SliceTricks.md
index 8783017a..71e2ab9e 100644
--- a/SliceTricks.md
+++ b/SliceTricks.md
@@ -104,10 +104,15 @@ s[i] = x
 #### InsertVector
 ```go
 a = append(a[:i], append(b, a[i:]...)...)
-```
 
-**NOTE**: To get the best efficiency, it is best to do the insertion without using `append`, in particular when the number of the inserted elements is known:
-```go
+// The above one-line way copies a[i:] twice and
+// might allocate at most twice.
+// The following verbose way only allocates at
+// most once and copy elements in a[i:] once.
+// But as of Go toolchain 1.16, due to lacking of
+// optimizations to avoid elements clearing in the
+// "make" call, the verbose way is not always faster.
+//
 // Assume element type is int.
 func Insert(s []int, k int, vs ...int) []int {
 	if n := len(s) + len(vs); n <= cap(s) {