diff --git a/tsdb/head_append.go b/tsdb/head_append.go
index 047701bf56..6f0f2a4f16 100644
--- a/tsdb/head_append.go
+++ b/tsdb/head_append.go
@@ -128,6 +128,7 @@ func (h *Head) appender() *headAppender {
 		mint:                  math.MaxInt64,
 		maxt:                  math.MinInt64,
 		headMaxt:              h.MaxTime(),
+		oooTimeWindow:         h.opts.OutOfOrderTimeWindow.Load(),
 		samples:               h.getAppendBuffer(),
 		sampleSeries:          h.getSeriesBuffer(),
 		exemplars:             exemplarsBuf,
@@ -236,10 +237,11 @@ type exemplarWithSeriesRef struct {
 }
 
 type headAppender struct {
-	head         *Head
-	minValidTime int64 // No samples below this timestamp are allowed.
-	mint, maxt   int64
-	headMaxt     int64 // We track it here to not take the lock for every sample appended.
+	head          *Head
+	minValidTime  int64 // No samples below this timestamp are allowed.
+	mint, maxt    int64
+	headMaxt      int64 // We track it here to not take the lock for every sample appended.
+	oooTimeWindow int64 // Use the same for the entire append, and don't load the atomic for each sample.
 
 	series       []record.RefSeries      // New series held by this appender.
 	samples      []record.RefSample      // New samples held by this appender.
@@ -253,8 +255,7 @@ type headAppender struct {
 func (a *headAppender) Append(ref storage.SeriesRef, lset labels.Labels, t int64, v float64) (storage.SeriesRef, error) {
 	// For OOO inserts, this restriction is irrelevant and will be checked later once we confirm the sample is an in-order append.
 	// If OOO inserts are disabled, we may as well as check this as early as we can and avoid more work.
-	oooTimeWindow := a.head.opts.OutOfOrderTimeWindow.Load()
-	if oooTimeWindow == 0 && t < a.minValidTime {
+	if a.oooTimeWindow == 0 && t < a.minValidTime {
 		a.head.metrics.outOfBoundSamples.Inc()
 		return 0, storage.ErrOutOfBounds
 	}
@@ -288,7 +289,7 @@ func (a *headAppender) Append(ref storage.SeriesRef, lset labels.Labels, t int64
 	s.Lock()
 	// TODO: if we definitely know at this point that the sample is ooo, then optimise
 	// to skip that sample from the WAL and write only in the WBL.
-	_, delta, err := s.appendable(t, v, a.headMaxt, a.minValidTime, oooTimeWindow)
+	_, delta, err := s.appendable(t, v, a.headMaxt, a.minValidTime, a.oooTimeWindow)
 	if err == nil {
 		s.pendingCommit = true
 	}
@@ -547,12 +548,11 @@ func (a *headAppender) Commit() (err error) {
 		wblSamples = nil
 		oooMmapMarkers = nil
 	}
-	oooTimeWindow := a.head.opts.OutOfOrderTimeWindow.Load()
 	for i, s := range a.samples {
 		series = a.sampleSeries[i]
 		series.Lock()
 
-		oooSample, _, err := series.appendable(s.T, s.V, a.headMaxt, a.minValidTime, oooTimeWindow)
+		oooSample, _, err := series.appendable(s.T, s.V, a.headMaxt, a.minValidTime, a.oooTimeWindow)
 		switch err {
 		case storage.ErrOutOfOrderSample:
 			samplesAppended--