diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/common/task/CachingLocalSegmentAllocatorHelper.java b/indexing-service/src/main/java/org/apache/druid/indexing/common/task/CachingLocalSegmentAllocatorHelper.java
index 1963fb4c2fdc..3c9bab2d9f5c 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/common/task/CachingLocalSegmentAllocatorHelper.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/common/task/CachingLocalSegmentAllocatorHelper.java
@@ -26,7 +26,6 @@
 import org.apache.druid.indexing.common.actions.SurrogateAction;
 import org.apache.druid.indexing.common.task.IndexTask.ShardSpecs;
 import org.apache.druid.java.util.common.ISE;
-import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.partition.ShardSpec;
 import org.joda.time.Interval;
@@ -133,6 +132,8 @@ public String getSequenceName(Interval interval, InputRow inputRow)
    */
   private String getSequenceName(Interval interval, ShardSpec shardSpec)
   {
-    return StringUtils.format("%s_%s_%d", taskId, interval, shardSpec.getPartitionNum());
+    // Note: We do not use String format here since this can be called in a tight loop
+    // and it's faster to add strings together than it is to use String#format
+    return taskId + "_" + interval + "_" + shardSpec.getPartitionNum();
   }
 }
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/RangePartitionCachingLocalSegmentAllocatorTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/RangePartitionCachingLocalSegmentAllocatorTest.java
index 6e91d10066af..dad9893a6b04 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/RangePartitionCachingLocalSegmentAllocatorTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/RangePartitionCachingLocalSegmentAllocatorTest.java
@@ -28,6 +28,7 @@
 import org.apache.druid.indexing.common.task.batch.parallel.distribution.PartitionBoundaries;
 import org.apache.druid.java.util.common.DateTimes;
 import org.apache.druid.java.util.common.Intervals;
+import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.SegmentId;
 import org.apache.druid.timeline.partition.SingleDimensionShardSpec;
@@ -141,6 +142,17 @@ public void allocatesCorrectShardSpecsForLastPartition()
     testAllocate(row, interval, partitionNum, null);
   }
 
+  @Test
+  public void getSequenceName()
+  {
+    // getSequenceName_forIntervalAndRow_shouldUseISOFormatAndPartitionNumForRow
+    Interval interval = INTERVAL_NORMAL;
+    InputRow row = createInputRow(interval, PARTITION9);
+    String sequenceName = target.getSequenceName(interval, row);
+    String expectedSequenceName = StringUtils.format("%s_%s_%d", TASKID, interval, 1);
+    Assert.assertEquals(expectedSequenceName, sequenceName);
+  }
+
   @SuppressWarnings("SameParameterValue")
   private void testAllocate(InputRow row, Interval interval, int partitionNum)
   {
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/HashPartitionCachingLocalSegmentAllocatorTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/HashPartitionCachingLocalSegmentAllocatorTest.java
index e82101d7386a..6230c8a888c6 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/HashPartitionCachingLocalSegmentAllocatorTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/HashPartitionCachingLocalSegmentAllocatorTest.java
@@ -31,6 +31,7 @@
 import org.apache.druid.java.util.common.DateTimes;
 import org.apache.druid.java.util.common.Intervals;
 import org.apache.druid.java.util.common.Pair;
+import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.SegmentId;
 import org.apache.druid.timeline.partition.HashBasedNumberedShardSpec;
@@ -101,6 +102,17 @@ public void allocatesCorrectShardSpec() throws IOException
     Assert.assertEquals(PARTITION_NUM, shardSpec.getPartitionNum());
   }
 
+
+  @Test
+  public void getSequenceName()
+  {
+    // getSequenceName_forIntervalAndRow_shouldUseISOFormatAndPartitionNumForRow
+    InputRow row = createInputRow();
+    String sequenceName = target.getSequenceName(INTERVAL, row);
+    String expectedSequenceName = StringUtils.format("%s_%s_%d", TASKID, INTERVAL, PARTITION_NUM);
+    Assert.assertEquals(expectedSequenceName, sequenceName);
+  }
+
   private static TaskToolbox createToolbox()
   {
     TaskToolbox toolbox = EasyMock.mock(TaskToolbox.class);