diff --git a/lineprotocol.go b/lineprotocol.go
index a5d99f6..5e84da0 100644
--- a/lineprotocol.go
+++ b/lineprotocol.go
@@ -117,13 +117,26 @@ func ReceiveNats(address string, handleLine func(dec *lineprotocol.Decoder) erro
 }
 
 func decodeLine(dec *lineprotocol.Decoder) error {
+	// Reduce allocations in loop:
+	t := time.Now()
+	metrics := make([]Metric, 0, 10)
+	selector := make([]string, 0, 4)
+	typeBuf, subTypeBuf := make([]byte, 0, 20), make([]byte, 0)
+
+	// Optimize for the case where all lines in a "batch" are about the same
+	// cluster and host. By using `WriteToLevel` (level = host), we do not need
+	// to take the root- and cluster-level lock as often.
+	var hostLevel *level = nil
+	var prevCluster, prevHost string = "", ""
+
 	for dec.Next() {
 		rawmeasurement, err := dec.Measurement()
 		if err != nil {
 			return err
 		}
 
-		var cluster, host, typeName, typeId, subType, subTypeId string
+		var cluster, host string
+		var typeName, typeId, subType, subTypeId []byte
 		for {
 			key, val, err := dec.NextTag()
 			if err != nil {
@@ -133,38 +146,61 @@ func decodeLine(dec *lineprotocol.Decoder) error {
 				break
 			}
 
+			// The go compiler optimizes string([]byte{...}) == "...":
 			switch string(key) {
 			case "cluster":
-				cluster = string(val)
+				if string(val) == prevCluster {
+					cluster = prevCluster
+				} else {
+					cluster = string(val)
+				}
 			case "hostname":
-				host = string(val)
+				if string(val) == prevHost {
+					host = prevHost
+				} else {
+					host = string(val)
+				}
 			case "type":
-				typeName = string(val)
+				typeName = val
 			case "type-id":
-				typeId = string(val)
+				typeId = val
 			case "subtype":
-				subType = string(val)
+				subType = val
 			case "stype-id":
-				subTypeId = string(val)
+				subTypeId = val
 			default:
 				// Ignore unkown tags (cc-metric-collector might send us a unit for example that we do not need)
 				// return fmt.Errorf("unkown tag: '%s' (value: '%s')", string(key), string(val))
 			}
 		}
 
-		selector := make([]string, 2, 4)
-		selector[0] = cluster
-		selector[1] = host
+		if hostLevel == nil || prevCluster != cluster || prevHost != host {
+			prevCluster = cluster
+			prevHost = host
+			selector = selector[:2]
+			selector[0] = cluster
+			selector[1] = host
+			hostLevel = memoryStore.root.findLevelOrCreate(selector, len(memoryStore.metrics))
+		}
+
+		selector = selector[:0]
 		if len(typeId) > 0 {
-			selector = append(selector, typeName+typeId)
+			typeBuf = typeBuf[:0]
+			typeBuf = append(typeBuf, typeName...)
+			typeBuf = append(typeBuf, typeId...)
+			selector = append(selector, string(typeBuf)) // <- Allocation :(
 			if len(subTypeId) > 0 {
-				selector = append(selector, subType+subTypeId)
+				subTypeBuf = subTypeBuf[:0]
+				subTypeBuf = append(subTypeBuf, subType...)
+				subTypeBuf = append(subTypeBuf, subTypeId...)
+				selector = append(selector, string(subTypeBuf))
 			}
 		}
 
-		metrics := make([]Metric, 0, 10)
-		measurement := string(rawmeasurement)
-		if measurement == "data" {
+		metrics = metrics[:0]
+		// A more dense lp format if supported if the measurement is 'data'.
+		// In that case, the field keys are used as metric names.
+		if string(rawmeasurement) == "data" {
 			for {
 				key, val, err := dec.NextField()
 				if err != nil {
@@ -185,11 +221,12 @@ func decodeLine(dec *lineprotocol.Decoder) error {
 				}
 
 				metrics = append(metrics, Metric{
-					Name:  string(key),
+					Name:  string(key), // <- Allocation :(
 					Value: value,
 				})
 			}
 		} else {
+			measurement := string(rawmeasurement) // <- Allocation :(
 			var value Float
 			for {
 				key, val, err := dec.NextField()
@@ -220,13 +257,13 @@ func decodeLine(dec *lineprotocol.Decoder) error {
 			})
 		}
 
-		t, err := dec.Time(lineprotocol.Second, time.Now())
+		t, err = dec.Time(lineprotocol.Second, t)
 		if err != nil {
 			return err
 		}
 
 		// log.Printf("write: %s (%v) -> %v\n", string(measurement), selector, value)
-		if err := memoryStore.Write(selector, t.Unix(), metrics); err != nil {
+		if err := memoryStore.WriteToLevel(hostLevel, selector, t.Unix(), metrics); err != nil {
 			return err
 		}
 	}
diff --git a/memstore.go b/memstore.go
index 5337fd8..339d195 100644
--- a/memstore.go
+++ b/memstore.go
@@ -2,7 +2,6 @@ package main
 
 import (
 	"errors"
-	"math"
 	"sync"
 )
 
@@ -39,13 +38,15 @@ type buffer struct {
 	prev, next *buffer // `prev` contains older data, `next` newer data.
 	archived   bool    // If true, this buffer is already archived
 
-	closed      bool
-	statisticts struct {
-		samples int
-		min     Float
-		max     Float
-		avg     Float
-	}
+	closed bool
+	/*
+		statisticts struct {
+			samples int
+			min     Float
+			max     Float
+			avg     Float
+		}
+	*/
 }
 
 func newBuffer(ts, freq int64) *buffer {
@@ -104,6 +105,9 @@ func (b *buffer) end() int64 {
 	return b.start + int64(len(b.data))*b.frequency
 }
 
+func (b *buffer) close() {}
+
+/*
 func (b *buffer) close() {
 	if b.closed {
 		return
@@ -134,6 +138,7 @@ func (b *buffer) close() {
 		b.statisticts.max = NaN
 	}
 }
+*/
 
 // func interpolate(idx int, data []Float) Float {
 // 	if idx == 0 || idx+1 == len(data) {
@@ -362,7 +367,11 @@ func NewMemoryStore(metrics map[string]MetricConfig) *MemoryStore {
 // Write all values in `metrics` to the level specified by `selector` for time `ts`.
 // Look at `findLevelOrCreate` for how selectors work.
 func (m *MemoryStore) Write(selector []string, ts int64, metrics []Metric) error {
-	l := m.root.findLevelOrCreate(selector, len(m.metrics))
+	return m.WriteToLevel(&m.root, selector, ts, metrics)
+}
+
+func (m *MemoryStore) WriteToLevel(l *level, selector []string, ts int64, metrics []Metric) error {
+	l = l.findLevelOrCreate(selector, len(m.metrics))
 	l.lock.Lock()
 	defer l.lock.Unlock()