diff --git a/CHANGELOG.md b/CHANGELOG.md
index ad436ceac3b..559da235c4a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,7 @@
 - [#6121](https://github.com/influxdata/influxdb/issues/6121): Fix panic: slice index out of bounds in TSM index
 - [#6140](https://github.com/influxdata/influxdb/issues/6140): Ensure Shard engine not accessed when closed.
 - [#6110](https://github.com/influxdata/influxdb/issues/6110): Fix for 0.9 upgrade path when using RPM
+- [#6131](https://github.com/influxdata/influxdb/issues/6061): Fix write throughput regression with large number of measurments
 
 ## v0.11.0 [2016-03-22]
 
diff --git a/tsdb/meta.go b/tsdb/meta.go
index feb10f8ffba..1adb578b9d0 100644
--- a/tsdb/meta.go
+++ b/tsdb/meta.go
@@ -158,9 +158,7 @@ func (d *DatabaseIndex) CreateMeasurementIndexIfNotExists(name string) *Measurem
 func (d *DatabaseIndex) AssignShard(k string, shardID uint64) {
 	ss := d.Series(k)
 	if ss != nil {
-		d.mu.Lock()
 		ss.AssignShard(shardID)
-		d.mu.Unlock()
 	}
 }
 
@@ -168,6 +166,7 @@ func (d *DatabaseIndex) AssignShard(k string, shardID uint64) {
 func (d *DatabaseIndex) TagsForSeries(key string) map[string]string {
 	d.mu.RLock()
 	defer d.mu.RUnlock()
+
 	ss := d.series[key]
 	if ss == nil {
 		return nil
@@ -375,8 +374,6 @@ func (d *DatabaseIndex) DropMeasurement(name string) {
 		delete(d.series, s.Key)
 	}
 
-	m.drop()
-
 	d.statMap.Add(statDatabaseSeries, int64(-len(m.seriesByID)))
 	d.statMap.Add(statDatabaseMeasurements, -1)
 }
@@ -418,8 +415,6 @@ type Measurement struct {
 	measurement         *Measurement
 	seriesByTagKeyValue map[string]map[string]SeriesIDs // map from tag key to value to sorted set of series ids
 	seriesIDs           SeriesIDs                       // sorted list of series IDs in this measurement
-
-	statMap *expvar.Map
 }
 
 // NewMeasurement allocates and initializes a new Measurement.
@@ -432,12 +427,6 @@ func NewMeasurement(name string, idx *DatabaseIndex) *Measurement {
 		seriesByID:          make(map[uint64]*Series),
 		seriesByTagKeyValue: make(map[string]map[string]SeriesIDs),
 		seriesIDs:           make(SeriesIDs, 0),
-
-		statMap: influxdb.NewStatistics(
-			fmt.Sprintf("measurement:%s.%s", name, idx.name),
-			"measurement",
-			map[string]string{"database": idx.name, "measurement": name},
-		),
 	}
 }
 
@@ -530,7 +519,6 @@ func (m *Measurement) AddSeries(s *Series) bool {
 		valueMap[v] = ids
 	}
 
-	m.statMap.Add(statMeasurementSeries, 1)
 	return true
 }
 
@@ -578,17 +566,9 @@ func (m *Measurement) DropSeries(seriesID uint64) {
 		}
 	}
 
-	m.statMap.Add(statMeasurementSeries, -1)
-
 	return
 }
 
-// drop handles any cleanup for when a measurement is dropped.
-// Currently only cleans up stats.
-func (m *Measurement) drop() {
-	m.statMap.Add(statMeasurementSeries, int64(-len(m.seriesIDs)))
-}
-
 // filters walks the where clause of a select statement and returns a map with all series ids
 // matching the where clause and any filter expression that should be applied to each
 func (m *Measurement) filters(condition influxql.Expr) (map[uint64]influxql.Expr, error) {
@@ -1311,9 +1291,9 @@ func (a Measurements) union(other Measurements) Measurements {
 
 // Series belong to a Measurement and represent unique time series in a database
 type Series struct {
-	Key  string
-	Tags map[string]string
-
+	mu          sync.RWMutex
+	Key         string
+	Tags        map[string]string
 	id          uint64
 	measurement *Measurement
 	shardIDs    map[uint64]bool // shards that have this series defined
@@ -1329,11 +1309,16 @@ func NewSeries(key string, tags map[string]string) *Series {
 }
 
 func (s *Series) AssignShard(shardID uint64) {
+	s.mu.Lock()
 	s.shardIDs[shardID] = true
+	s.mu.Unlock()
 }
 
 // MarshalBinary encodes the object to a binary format.
 func (s *Series) MarshalBinary() ([]byte, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
 	var pb internal.Series
 	pb.Key = &s.Key
 	for k, v := range s.Tags {
@@ -1346,6 +1331,9 @@ func (s *Series) MarshalBinary() ([]byte, error) {
 
 // UnmarshalBinary decodes the object from a binary format.
 func (s *Series) UnmarshalBinary(buf []byte) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
 	var pb internal.Series
 	if err := proto.Unmarshal(buf, &pb); err != nil {
 		return err
@@ -1360,17 +1348,9 @@ func (s *Series) UnmarshalBinary(buf []byte) error {
 
 // InitializeShards initializes the list of shards.
 func (s *Series) InitializeShards() {
+	s.mu.Lock()
 	s.shardIDs = make(map[uint64]bool)
-}
-
-// match returns true if all tags match the series' tags.
-func (s *Series) match(tags map[string]string) bool {
-	for k, v := range tags {
-		if s.Tags[k] != v {
-			return false
-		}
-	}
-	return true
+	s.mu.Unlock()
 }
 
 // SeriesIDs is a convenience type for sorting, checking equality, and doing