diff --git a/CHANGELOG.md b/CHANGELOG.md
index 33cd0f54285..5425a82c494 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
 * [ENHANCEMENT] Add docker-compose example for GCS along with new backend options [#397](https://github.com/grafana/tempo/pull/397)
 * [ENHANCEMENT] tempo-cli list blocks usability improvements [#403](https://github.com/grafana/tempo/pull/403)
 * [ENHANCEMENT] Add Query Frontend module to allow scaling the query path [#400](https://github.com/grafana/tempo/pull/400)
+* [ENHANCEMENT] Reduce active traces locking time. [#449](https://github.com/grafana/tempo/pull/449)
 * [ENHANCEMENT] Added `tempo_distributor_bytes_received_total` as a per tenant counter of uncompressed bytes received. [#453](https://github.com/grafana/tempo/pull/453)
 * [BUGFIX] Compactor without GCS permissions fail silently [#379](https://github.com/grafana/tempo/issues/379)
 * [BUGFIX] Prevent race conditions between querier polling and ingesters clearing complete blocks [#421](https://github.com/grafana/tempo/issues/421)
diff --git a/modules/ingester/instance.go b/modules/ingester/instance.go
index 094859bfe5f..b1a2b1d2252 100644
--- a/modules/ingester/instance.go
+++ b/modules/ingester/instance.go
@@ -113,26 +113,21 @@ func (i *instance) PushBytes(ctx context.Context, id tempodb_encoding.ID, object
 
 // Moves any complete traces out of the map to complete traces
 func (i *instance) CutCompleteTraces(cutoff time.Duration, immediate bool) error {
-	i.tracesMtx.Lock()
-	defer i.tracesMtx.Unlock()
+	tracesToCut := i.tracesToCut(cutoff, immediate)
 
 	i.blocksMtx.Lock()
 	defer i.blocksMtx.Unlock()
 
-	now := time.Now()
-	for key, trace := range i.traces {
-		if now.Add(cutoff).After(trace.lastAppend) || immediate {
-			out, err := proto.Marshal(trace.trace)
-			if err != nil {
-				return err
-			}
-			err = i.headBlock.Write(trace.traceID, out)
-			if err != nil {
-				return err
-			}
-			i.bytesWrittenTotal.Add(float64(len(out)))
-			delete(i.traces, key)
+	for _, t := range tracesToCut {
+		out, err := proto.Marshal(t.trace)
+		if err != nil {
+			return err
+		}
+		err = i.headBlock.Write(t.traceID, out)
+		if err != nil {
+			return err
 		}
+		i.bytesWrittenTotal.Add(float64(len(out)))
 	}
 
 	return nil
@@ -277,6 +272,8 @@ func (i *instance) FindTraceByID(id []byte) (*tempopb.Trace, error) {
 	return nil, nil
 }
 
+// getOrCreateTrace will return a new trace object for the given request
+//  It must be called under the i.tracesMtx lock
 func (i *instance) getOrCreateTrace(req *tempopb.PushRequest) (*trace, error) {
 	traceID, err := pushRequestTraceID(req)
 	if err != nil {
@@ -317,6 +314,23 @@ func (i *instance) resetHeadBlock() error {
 	return err
 }
 
+func (i *instance) tracesToCut(cutoff time.Duration, immediate bool) []*trace {
+	i.tracesMtx.Lock()
+	defer i.tracesMtx.Unlock()
+
+	cutoffTime := time.Now().Add(cutoff)
+	tracesToCut := make([]*trace, 0, len(i.traces))
+
+	for key, trace := range i.traces {
+		if cutoffTime.After(trace.lastAppend) || immediate {
+			tracesToCut = append(tracesToCut, trace)
+			delete(i.traces, key)
+		}
+	}
+
+	return tracesToCut
+}
+
 func (i *instance) Combine(objA []byte, objB []byte) []byte {
 	return util.CombineTraces(objA, objB)
 }
diff --git a/modules/ingester/instance_test.go b/modules/ingester/instance_test.go
index a52e8713c1b..91de03d7e39 100644
--- a/modules/ingester/instance_test.go
+++ b/modules/ingester/instance_test.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/binary"
 	"io/ioutil"
+	"math/rand"
 	"os"
 	"testing"
 	"time"
@@ -14,6 +15,7 @@ import (
 	"github.com/grafana/tempo/tempodb/wal"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 type ringCountMock struct {
@@ -255,6 +257,90 @@ func TestInstanceLimits(t *testing.T) {
 	}
 }
 
+func TestInstanceCutCompleteTraces(t *testing.T) {
+	tempDir, _ := ioutil.TempDir("/tmp", "")
+	defer os.RemoveAll(tempDir)
+
+	id := make([]byte, 16)
+	rand.Read(id)
+	tracepb := test.MakeTrace(10, id)
+	pastTrace := &trace{
+		traceID:    id,
+		trace:      tracepb,
+		lastAppend: time.Now().Add(-time.Hour),
+	}
+
+	id = make([]byte, 16)
+	rand.Read(id)
+	nowTrace := &trace{
+		traceID:    id,
+		trace:      tracepb,
+		lastAppend: time.Now().Add(time.Hour),
+	}
+
+	tt := []struct {
+		name             string
+		cutoff           time.Duration
+		immediate        bool
+		input            []*trace
+		expectedExist    []*trace
+		expectedNotExist []*trace
+	}{
+		{
+			name:      "empty",
+			cutoff:    0,
+			immediate: false,
+		},
+		{
+			name:             "cut immediate",
+			cutoff:           0,
+			immediate:        true,
+			input:            []*trace{pastTrace, nowTrace},
+			expectedNotExist: []*trace{pastTrace, nowTrace},
+		},
+		{
+			name:             "cut recent",
+			cutoff:           0,
+			immediate:        false,
+			input:            []*trace{pastTrace, nowTrace},
+			expectedExist:    []*trace{nowTrace},
+			expectedNotExist: []*trace{pastTrace},
+		},
+		{
+			name:             "cut all time",
+			cutoff:           2 * time.Hour,
+			immediate:        false,
+			input:            []*trace{pastTrace, nowTrace},
+			expectedNotExist: []*trace{pastTrace, nowTrace},
+		},
+	}
+
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			instance := defaultInstance(t, tempDir)
+
+			for _, trace := range tc.input {
+				fp := instance.tokenForTraceID(trace.traceID)
+				instance.traces[fp] = trace
+			}
+
+			err := instance.CutCompleteTraces(tc.cutoff, tc.immediate)
+			require.NoError(t, err)
+
+			assert.Equal(t, len(tc.expectedExist), len(instance.traces))
+			for _, expectedExist := range tc.expectedExist {
+				_, ok := instance.traces[instance.tokenForTraceID(expectedExist.traceID)]
+				assert.True(t, ok)
+			}
+
+			for _, expectedNotExist := range tc.expectedNotExist {
+				_, ok := instance.traces[instance.tokenForTraceID(expectedNotExist.traceID)]
+				assert.False(t, ok)
+			}
+		})
+	}
+}
+
 func defaultInstance(t assert.TestingT, tempDir string) *instance {
 	limits, err := overrides.NewOverrides(overrides.Limits{})
 	assert.NoError(t, err, "unexpected error creating limits")