diff --git a/tsdb/chunks/chunk_write_queue.go b/tsdb/chunks/chunk_write_queue.go
index 5cdd2e81f0..e7b9a4cc3c 100644
--- a/tsdb/chunks/chunk_write_queue.go
+++ b/tsdb/chunks/chunk_write_queue.go
@@ -22,6 +22,8 @@ import (
 	"github.com/prometheus/prometheus/tsdb/chunkenc"
 )
 
+const chunkRefMapFreeThreshold = 10
+
 type chunkWriteJob struct {
 	cutFile   bool
 	seriesRef HeadSeriesRef
@@ -38,8 +40,9 @@ type chunkWriteJob struct {
 type chunkWriteQueue struct {
 	jobs chan chunkWriteJob
 
-	chunkRefMapMtx sync.RWMutex
-	chunkRefMap    map[ChunkDiskMapperRef]chunkenc.Chunk
+	chunkRefMapMtx  sync.RWMutex
+	chunkRefMap     map[ChunkDiskMapperRef]chunkenc.Chunk
+	chunkRefMapPeak int
 
 	isRunningMtx sync.Mutex // Protects the isRunning property.
 	isRunning    bool       // Used to prevent that new jobs get added to the queue when the chan is already closed.
@@ -69,7 +72,7 @@ func newChunkWriteQueue(reg prometheus.Registerer, size int, writeChunk writeChu
 
 	q := &chunkWriteQueue{
 		jobs:        make(chan chunkWriteJob, size),
-		chunkRefMap: make(map[ChunkDiskMapperRef]chunkenc.Chunk, size),
+		chunkRefMap: make(map[ChunkDiskMapperRef]chunkenc.Chunk),
 		writeChunk:  writeChunk,
 
 		adds:      counters.WithLabelValues("add"),
@@ -112,6 +115,14 @@ func (c *chunkWriteQueue) processJob(job chunkWriteJob) {
 	delete(c.chunkRefMap, job.ref)
 
 	c.completed.Inc()
+
+	if len(c.chunkRefMap) == 0 && c.chunkRefMapPeak > chunkRefMapFreeThreshold {
+		// Re-initialize the chunk ref map to half of the peak size that was in use since the last re-init event.
+		// By setting it to half of the peak we try to minimize the number of allocations required for a "normal" usage
+		// while ensuring that if its usage has decreased we shrink it over time.
+		c.chunkRefMap = make(map[ChunkDiskMapperRef]chunkenc.Chunk, c.chunkRefMapPeak/2)
+		c.chunkRefMapPeak = 0
+	}
 }
 
 func (c *chunkWriteQueue) addJob(job chunkWriteJob) (err error) {
@@ -121,6 +132,8 @@ func (c *chunkWriteQueue) addJob(job chunkWriteJob) (err error) {
 		}
 	}()
 
+	// c.isRunningMtx serializes the adding of jobs to the c.chunkRefMap, if c.jobs is full then c.addJob() will block
+	// while holding c.isRunningMtx, this guarantees that c.chunkRefMap won't ever grow beyond the queue size + 1.
 	c.isRunningMtx.Lock()
 	defer c.isRunningMtx.Unlock()
 
@@ -130,6 +143,11 @@ func (c *chunkWriteQueue) addJob(job chunkWriteJob) (err error) {
 
 	c.chunkRefMapMtx.Lock()
 	c.chunkRefMap[job.ref] = job.chk
+
+	// Keep track of the peak usage of c.chunkRefMap.
+	if len(c.chunkRefMap) > c.chunkRefMapPeak {
+		c.chunkRefMapPeak = len(c.chunkRefMap)
+	}
 	c.chunkRefMapMtx.Unlock()
 
 	c.jobs <- job