diff --git a/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/PrometheusTextFormatWriter.java b/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/PrometheusTextFormatWriter.java
index eb07abc73..8602b0ba5 100644
--- a/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/PrometheusTextFormatWriter.java
+++ b/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/PrometheusTextFormatWriter.java
@@ -20,6 +20,7 @@
 import io.prometheus.metrics.model.snapshots.StateSetSnapshot;
 import io.prometheus.metrics.model.snapshots.SummarySnapshot;
 import io.prometheus.metrics.model.snapshots.UnknownSnapshot;
+import java.io.BufferedWriter;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
@@ -59,7 +60,7 @@ public void write(OutputStream out, MetricSnapshots metricSnapshots) throws IOEx
     // See https://prometheus.io/docs/instrumenting/exposition_formats/
     // "unknown", "gauge", "counter", "stateset", "info", "histogram", "gaugehistogram", and
     // "summary".
-    OutputStreamWriter writer = new OutputStreamWriter(out, StandardCharsets.UTF_8);
+    Writer writer = new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.UTF_8));
     for (MetricSnapshot snapshot : metricSnapshots) {
       if (snapshot.getDataPoints().size() > 0) {
         if (snapshot instanceof CounterSnapshot) {
@@ -95,7 +96,7 @@ public void write(OutputStream out, MetricSnapshots metricSnapshots) throws IOEx
     writer.flush();
   }
 
-  public void writeCreated(OutputStreamWriter writer, MetricSnapshot snapshot) throws IOException {
+  public void writeCreated(Writer writer, MetricSnapshot snapshot) throws IOException {
     boolean metadataWritten = false;
     MetricMetadata metadata = snapshot.getMetadata();
     for (DataPointSnapshot data : snapshot.getDataPoints()) {
@@ -111,8 +112,7 @@ public void writeCreated(OutputStreamWriter writer, MetricSnapshot snapshot) thr
     }
   }
 
-  private void writeCounter(OutputStreamWriter writer, CounterSnapshot snapshot)
-      throws IOException {
+  private void writeCounter(Writer writer, CounterSnapshot snapshot) throws IOException {
     if (snapshot.getDataPoints().size() > 0) {
       MetricMetadata metadata = snapshot.getMetadata();
       writeMetadata(writer, "_total", "counter", metadata);
@@ -124,7 +124,7 @@ private void writeCounter(OutputStreamWriter writer, CounterSnapshot snapshot)
     }
   }
 
-  private void writeGauge(OutputStreamWriter writer, GaugeSnapshot snapshot) throws IOException {
+  private void writeGauge(Writer writer, GaugeSnapshot snapshot) throws IOException {
     MetricMetadata metadata = snapshot.getMetadata();
     writeMetadata(writer, "", "gauge", metadata);
     for (GaugeSnapshot.GaugeDataPointSnapshot data : snapshot.getDataPoints()) {
@@ -134,8 +134,7 @@ private void writeGauge(OutputStreamWriter writer, GaugeSnapshot snapshot) throw
     }
   }
 
-  private void writeHistogram(OutputStreamWriter writer, HistogramSnapshot snapshot)
-      throws IOException {
+  private void writeHistogram(Writer writer, HistogramSnapshot snapshot) throws IOException {
     MetricMetadata metadata = snapshot.getMetadata();
     writeMetadata(writer, "", "histogram", metadata);
     for (HistogramSnapshot.HistogramDataPointSnapshot data : snapshot.getDataPoints()) {
@@ -182,8 +181,7 @@ private ClassicHistogramBuckets getClassicBuckets(
   }
 
   private void writeGaugeCountSum(
-      OutputStreamWriter writer, HistogramSnapshot snapshot, MetricMetadata metadata)
-      throws IOException {
+      Writer writer, HistogramSnapshot snapshot, MetricMetadata metadata) throws IOException {
     // Prometheus text format does not support gaugehistogram's _gcount and _gsum.
     // So we append _gcount and _gsum as gauge metrics.
     boolean metadataWritten = false;
@@ -212,8 +210,7 @@ private void writeGaugeCountSum(
     }
   }
 
-  private void writeSummary(OutputStreamWriter writer, SummarySnapshot snapshot)
-      throws IOException {
+  private void writeSummary(Writer writer, SummarySnapshot snapshot) throws IOException {
     boolean metadataWritten = false;
     MetricMetadata metadata = snapshot.getMetadata();
     for (SummarySnapshot.SummaryDataPointSnapshot data : snapshot.getDataPoints()) {
@@ -248,7 +245,7 @@ private void writeSummary(OutputStreamWriter writer, SummarySnapshot snapshot)
     }
   }
 
-  private void writeInfo(OutputStreamWriter writer, InfoSnapshot snapshot) throws IOException {
+  private void writeInfo(Writer writer, InfoSnapshot snapshot) throws IOException {
     MetricMetadata metadata = snapshot.getMetadata();
     writeMetadata(writer, "_info", "gauge", metadata);
     for (InfoSnapshot.InfoDataPointSnapshot data : snapshot.getDataPoints()) {
@@ -258,8 +255,7 @@ private void writeInfo(OutputStreamWriter writer, InfoSnapshot snapshot) throws
     }
   }
 
-  private void writeStateSet(OutputStreamWriter writer, StateSetSnapshot snapshot)
-      throws IOException {
+  private void writeStateSet(Writer writer, StateSetSnapshot snapshot) throws IOException {
     MetricMetadata metadata = snapshot.getMetadata();
     writeMetadata(writer, "", "gauge", metadata);
     for (StateSetSnapshot.StateSetDataPointSnapshot data : snapshot.getDataPoints()) {
@@ -292,8 +288,7 @@ private void writeStateSet(OutputStreamWriter writer, StateSetSnapshot snapshot)
     }
   }
 
-  private void writeUnknown(OutputStreamWriter writer, UnknownSnapshot snapshot)
-      throws IOException {
+  private void writeUnknown(Writer writer, UnknownSnapshot snapshot) throws IOException {
     MetricMetadata metadata = snapshot.getMetadata();
     writeMetadata(writer, "", "untyped", metadata);
     for (UnknownSnapshot.UnknownDataPointSnapshot data : snapshot.getDataPoints()) {
@@ -303,13 +298,13 @@ private void writeUnknown(OutputStreamWriter writer, UnknownSnapshot snapshot)
     }
   }
 
-  private void writeNameAndLabels(
-      OutputStreamWriter writer, String name, String suffix, Labels labels) throws IOException {
+  private void writeNameAndLabels(Writer writer, String name, String suffix, Labels labels)
+      throws IOException {
     writeNameAndLabels(writer, name, suffix, labels, null, 0.0);
   }
 
   private void writeNameAndLabels(
-      OutputStreamWriter writer,
+      Writer writer,
       String name,
       String suffix,
       Labels labels,
@@ -327,8 +322,7 @@ private void writeNameAndLabels(
   }
 
   private void writeMetadata(
-      OutputStreamWriter writer, String suffix, String typeString, MetricMetadata metadata)
-      throws IOException {
+      Writer writer, String suffix, String typeString, MetricMetadata metadata) throws IOException {
     if (metadata.getHelp() != null && !metadata.getHelp().isEmpty()) {
       writer.write("# HELP ");
       writer.write(metadata.getPrometheusName());
@@ -365,7 +359,7 @@ private void writeEscapedHelp(Writer writer, String s) throws IOException {
     }
   }
 
-  private void writeScrapeTimestampAndNewline(OutputStreamWriter writer, DataPointSnapshot data)
+  private void writeScrapeTimestampAndNewline(Writer writer, DataPointSnapshot data)
       throws IOException {
     if (data.hasScrapeTimestamp()) {
       writer.write(' ');
diff --git a/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/TextFormatUtil.java b/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/TextFormatUtil.java
index 54daaaa3e..e48f545c5 100644
--- a/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/TextFormatUtil.java
+++ b/prometheus-metrics-exposition-textformats/src/main/java/io/prometheus/metrics/expositionformats/TextFormatUtil.java
@@ -2,16 +2,15 @@
 
 import io.prometheus.metrics.model.snapshots.Labels;
 import java.io.IOException;
-import java.io.OutputStreamWriter;
 import java.io.Writer;
 
 public class TextFormatUtil {
 
-  static void writeLong(OutputStreamWriter writer, long value) throws IOException {
+  static void writeLong(Writer writer, long value) throws IOException {
     writer.append(Long.toString(value));
   }
 
-  static void writeDouble(OutputStreamWriter writer, double d) throws IOException {
+  static void writeDouble(Writer writer, double d) throws IOException {
     if (d == Double.POSITIVE_INFINITY) {
       writer.write("+Inf");
     } else if (d == Double.NEGATIVE_INFINITY) {
@@ -22,7 +21,7 @@ static void writeDouble(OutputStreamWriter writer, double d) throws IOException
     }
   }
 
-  static void writeTimestamp(OutputStreamWriter writer, long timestampMs) throws IOException {
+  static void writeTimestamp(Writer writer, long timestampMs) throws IOException {
     writer.write(Long.toString(timestampMs / 1000L));
     writer.write(".");
     long ms = timestampMs % 1000;
@@ -55,10 +54,7 @@ static void writeEscapedLabelValue(Writer writer, String s) throws IOException {
   }
 
   static void writeLabels(
-      OutputStreamWriter writer,
-      Labels labels,
-      String additionalLabelName,
-      double additionalLabelValue)
+      Writer writer, Labels labels, String additionalLabelName, double additionalLabelValue)
       throws IOException {
     writer.write('{');
     for (int i = 0; i < labels.size(); i++) {