From 12d45415bb6986c6fd3b689fb15d21d5e892238f Mon Sep 17 00:00:00 2001
From: Richard Artoul <rartoul@uber.com>
Date: Thu, 29 Nov 2018 17:29:32 -0500
Subject: [PATCH] more refactoring and micro optimizations

---
 roaring/roaring.go | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/roaring/roaring.go b/roaring/roaring.go
index 7b382ec6f..575515743 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -659,8 +659,9 @@ func (b *Bitmap) unionIntoTarget(target *Bitmap, others ...*Bitmap) {
 				// Once we've acquired a bitmap container (either by reusing the existing one
 				// or allocating a new one) then the last step is to iterate through all the
 				// other containers to see which ones have the same key, and union all of them
-				// into the target bitmap container.
-				for j, jIter := range bitmapIters {
+				// into the target bitmap container. Only need to loop starting from i because
+				// anything previous to that has already been handled.
+				for j, jIter := range bitmapIters[i:] {
 					jKey, jContainer := jIter.iter.Value()
 
 					if iKey == jKey {