diff --git a/native/shuffle/src/bin/shuffle_bench.rs b/native/shuffle/src/bin/shuffle_bench.rs
index bb8c2a0380..cc1c960848 100644
--- a/native/shuffle/src/bin/shuffle_bench.rs
+++ b/native/shuffle/src/bin/shuffle_bench.rs
@@ -277,6 +277,9 @@ fn print_shuffle_metrics(metrics: &MetricsSet, total_wall_time_secs: f64) {
     if let Some(nanos) = get_metric("repart_time") {
         println!("  repart time:      {}", fmt_time(nanos));
     }
+    if let Some(nanos) = get_metric("interleave_time") {
+        println!("  interleave time:  {}", fmt_time(nanos));
+    }
     if let Some(nanos) = get_metric("encode_time") {
         println!("  encode time:      {}", fmt_time(nanos));
     }
diff --git a/native/shuffle/src/metrics.rs b/native/shuffle/src/metrics.rs
index 1de751cf41..bda245fd93 100644
--- a/native/shuffle/src/metrics.rs
+++ b/native/shuffle/src/metrics.rs
@@ -27,6 +27,9 @@ pub(crate) struct ShufflePartitionerMetrics {
     /// Time to perform repartitioning
     pub(crate) repart_time: Time,
 
+    /// Time spent in `interleave_record_batch` gathering shuffled batches
+    pub(crate) interleave_time: Time,
+
     /// Time encoding batches to IPC format
     pub(crate) encode_time: Time,
 
@@ -51,6 +54,7 @@ impl ShufflePartitionerMetrics {
         Self {
             baseline: BaselineMetrics::new(metrics, partition),
             repart_time: MetricBuilder::new(metrics).subset_time("repart_time", partition),
+            interleave_time: MetricBuilder::new(metrics).subset_time("interleave_time", partition),
             encode_time: MetricBuilder::new(metrics).subset_time("encode_time", partition),
             write_time: MetricBuilder::new(metrics).subset_time("write_time", partition),
             input_batches: MetricBuilder::new(metrics).counter("input_batches", partition),
diff --git a/native/shuffle/src/partitioners/multi_partition.rs b/native/shuffle/src/partitioners/multi_partition.rs
index 7de9314f54..aa44cad4d5 100644
--- a/native/shuffle/src/partitioners/multi_partition.rs
+++ b/native/shuffle/src/partitioners/multi_partition.rs
@@ -434,10 +434,12 @@ impl MultiPartitionShuffleRepartitioner {
         Ok(())
     }
 
+    #[allow(clippy::too_many_arguments)]
     fn shuffle_write_partition(
         partition_iter: &mut PartitionedBatchIterator,
         shuffle_block_writer: &mut ShuffleBlockWriter,
         output_data: &mut BufWriter<File>,
+        interleave_time: &Time,
         encode_time: &Time,
         write_time: &Time,
         write_buffer_size: usize,
@@ -449,7 +451,7 @@ impl MultiPartitionShuffleRepartitioner {
             write_buffer_size,
             batch_size,
         );
-        for batch in partition_iter {
+        while let Some(batch) = partition_iter.next(interleave_time) {
             let batch = batch?;
             buf_batch_writer.write(&batch, encode_time, write_time)?;
         }
@@ -573,7 +575,7 @@ impl ShufflePartitioner for MultiPartitionShuffleRepartitioner {
                 .open(data_file)
                 .map_err(|e| DataFusionError::Execution(format!("shuffle write error: {e:?}")))?;
 
-            let mut output_data = BufWriter::new(output_data);
+            let mut output_data = BufWriter::with_capacity(self.write_buffer_size, output_data);
 
             #[allow(clippy::needless_range_loop)]
             for i in 0..num_output_partitions {
@@ -596,6 +598,7 @@ impl ShufflePartitioner for MultiPartitionShuffleRepartitioner {
                     &mut partition_iter,
                     &mut self.shuffle_block_writer,
                     &mut output_data,
+                    &self.metrics.interleave_time,
                     &self.metrics.encode_time,
                     &self.metrics.write_time,
                     self.write_buffer_size,
diff --git a/native/shuffle/src/partitioners/partitioned_batch_iterator.rs b/native/shuffle/src/partitioners/partitioned_batch_iterator.rs
index 8309a8ed4a..c7f1781866 100644
--- a/native/shuffle/src/partitioners/partitioned_batch_iterator.rs
+++ b/native/shuffle/src/partitioners/partitioned_batch_iterator.rs
@@ -18,6 +18,7 @@
 use arrow::array::RecordBatch;
 use arrow::compute::interleave_record_batch;
 use datafusion::common::DataFusionError;
+use datafusion::physical_plan::metrics::Time;
 
 /// A helper struct to produce shuffled batches.
 /// This struct takes ownership of the buffered batches and partition indices from the
@@ -85,19 +86,22 @@ impl<'a> PartitionedBatchIterator<'a> {
             pos: 0,
         }
     }
-}
-
-impl Iterator for PartitionedBatchIterator<'_> {
-    type Item = datafusion::common::Result<RecordBatch>;
 
-    fn next(&mut self) -> Option<Self::Item> {
+    /// Returns the next shuffled batch, recording the gather cost into `interleave_time`.
+    pub(crate) fn next(
+        &mut self,
+        interleave_time: &Time,
+    ) -> Option<datafusion::common::Result<RecordBatch>> {
         if self.pos >= self.indices.len() {
             return None;
         }
 
         let indices_end = std::cmp::min(self.pos + self.batch_size, self.indices.len());
         let indices = &self.indices[self.pos..indices_end];
-        match interleave_record_batch(&self.record_batches, indices) {
+        let mut timer = interleave_time.timer();
+        let result = interleave_record_batch(&self.record_batches, indices);
+        timer.stop();
+        match result {
             Ok(batch) => {
                 self.pos = indices_end;
                 Some(Ok(batch))
diff --git a/native/shuffle/src/writers/spill.rs b/native/shuffle/src/writers/spill.rs
index c16caddbf9..624a45befe 100644
--- a/native/shuffle/src/writers/spill.rs
+++ b/native/shuffle/src/writers/spill.rs
@@ -83,7 +83,7 @@ impl PartitionWriter {
         write_buffer_size: usize,
         batch_size: usize,
     ) -> datafusion::common::Result<usize> {
-        if let Some(batch) = iter.next() {
+        if let Some(batch) = iter.next(&metrics.interleave_time) {
             self.ensure_spill_file_created(runtime)?;
 
             let total_bytes_written = {
@@ -95,7 +95,7 @@ impl PartitionWriter {
                 );
                 let mut bytes_written =
                     buf_batch_writer.write(&batch?, &metrics.encode_time, &metrics.write_time)?;
-                for batch in iter {
+                while let Some(batch) = iter.next(&metrics.interleave_time) {
                     let batch = batch?;
                     bytes_written += buf_batch_writer.write(
                         &batch,