diff --git a/jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/GZIPContentDecoder.java b/jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/GZIPContentDecoder.java
index cb6213a8405..95ad573cfec 100644
--- a/jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/GZIPContentDecoder.java
+++ b/jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/GZIPContentDecoder.java
@@ -20,13 +20,14 @@ import org.eclipse.jetty.http.HttpField;
 import org.eclipse.jetty.http.HttpHeader;
 import org.eclipse.jetty.io.ByteBufferPool;
 import org.eclipse.jetty.io.RetainableByteBuffer;
+import org.eclipse.jetty.util.IO;
 
 /**
  * {@link ContentDecoder} for the "gzip" encoding.
  */
 public class GZIPContentDecoder extends org.eclipse.jetty.http.GZIPContentDecoder implements ContentDecoder
 {
-    public static final int DEFAULT_BUFFER_SIZE = 8192;
+    public static final int DEFAULT_BUFFER_SIZE = IO.DEFAULT_BUFFER_SIZE;
 
     private long decodedLength;
 
diff --git a/jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/HttpTester.java b/jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/HttpTester.java
index 34297bcd153..a019dfb2cf6 100644
--- a/jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/HttpTester.java
+++ b/jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/HttpTester.java
@@ -23,6 +23,7 @@ import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 
 import org.eclipse.jetty.util.BufferUtil;
+import org.eclipse.jetty.util.IO;
 import org.eclipse.jetty.util.StringUtil;
 
 /**
@@ -62,7 +63,7 @@ public class HttpTester
 
         public Input()
         {
-            this(BufferUtil.allocate(8192));
+            this(BufferUtil.allocate(IO.DEFAULT_BUFFER_SIZE));
         }
 
         Input(ByteBuffer buffer)
@@ -477,7 +478,7 @@ public class HttpTester
                     switch (result)
                     {
                         case NEED_HEADER:
-                            header = BufferUtil.allocate(8192);
+                            header = BufferUtil.allocate(IO.DEFAULT_BUFFER_SIZE);
                             continue;
 
                         case HEADER_OVERFLOW:
@@ -491,7 +492,7 @@ public class HttpTester
                             continue;
 
                         case NEED_CHUNK_TRAILER:
-                            chunk = BufferUtil.allocate(8192);
+                            chunk = BufferUtil.allocate(IO.DEFAULT_BUFFER_SIZE);
                             continue;
 
                         case NEED_INFO:
diff --git a/jetty-core/jetty-http2/jetty-http2-client/src/main/java/org/eclipse/jetty/http2/client/HTTP2Client.java b/jetty-core/jetty-http2/jetty-http2-client/src/main/java/org/eclipse/jetty/http2/client/HTTP2Client.java
index b49687bac79..442e6ab52a0 100644
--- a/jetty-core/jetty-http2/jetty-http2-client/src/main/java/org/eclipse/jetty/http2/client/HTTP2Client.java
+++ b/jetty-core/jetty-http2/jetty-http2-client/src/main/java/org/eclipse/jetty/http2/client/HTTP2Client.java
@@ -34,6 +34,7 @@ import org.eclipse.jetty.io.ClientConnectionFactory;
 import org.eclipse.jetty.io.ClientConnector;
 import org.eclipse.jetty.io.Transport;
 import org.eclipse.jetty.io.ssl.SslClientConnectionFactory;
+import org.eclipse.jetty.util.IO;
 import org.eclipse.jetty.util.Promise;
 import org.eclipse.jetty.util.annotation.ManagedAttribute;
 import org.eclipse.jetty.util.annotation.ManagedObject;
@@ -102,7 +103,7 @@ import org.eclipse.jetty.util.thread.Scheduler;
 public class HTTP2Client extends ContainerLifeCycle
 {
     private final ClientConnector connector;
-    private int inputBufferSize = 8192;
+    private int inputBufferSize = IO.DEFAULT_BUFFER_SIZE;
     private List<String> protocols = List.of("h2");
     private int initialSessionRecvWindow = 16 * 1024 * 1024;
     private int initialStreamRecvWindow = 8 * 1024 * 1024;
diff --git a/jetty-core/jetty-http3/jetty-http3-common/src/main/java/org/eclipse/jetty/http3/HTTP3Configuration.java b/jetty-core/jetty-http3/jetty-http3-common/src/main/java/org/eclipse/jetty/http3/HTTP3Configuration.java
index 2d73fdd80ee..4f34e4cd039 100644
--- a/jetty-core/jetty-http3/jetty-http3-common/src/main/java/org/eclipse/jetty/http3/HTTP3Configuration.java
+++ b/jetty-core/jetty-http3/jetty-http3-common/src/main/java/org/eclipse/jetty/http3/HTTP3Configuration.java
@@ -13,6 +13,7 @@
 
 package org.eclipse.jetty.http3;
 
+import org.eclipse.jetty.util.IO;
 import org.eclipse.jetty.util.annotation.ManagedAttribute;
 import org.eclipse.jetty.util.annotation.ManagedObject;
 
@@ -186,7 +187,7 @@ public class HTTP3Configuration
 
     /**
      * <p>Sets max request headers size.</p>
-     * <p>The default value is {@code 8192} bytes.</p>
+     * <p>The default value is {@link IO#DEFAULT_BUFFER_SIZE} bytes.</p>
      * <p>This value is configured in the server-side QPACK decoder, and
      * then communicated to the client-side QPACK encoder via the SETTINGS
      * frame.</p>
@@ -208,7 +209,7 @@ public class HTTP3Configuration
 
     /**
      * <p>Sets max response headers size.</p>
-     * <p>The default value is {@code 8192} bytes.</p>
+     * <p>The default value is {@link IO#DEFAULT_BUFFER_SIZE} bytes.</p>
      * <p>This value is configured in the client-side QPACK decoder, and
      * then communicated to the server-side QPACK encoder via the SETTINGS
      * frame.</p>
diff --git a/jetty-core/jetty-io/src/main/java/org/eclipse/jetty/io/ByteBufferPool.java b/jetty-core/jetty-io/src/main/java/org/eclipse/jetty/io/ByteBufferPool.java
index bfb14d4d800..6a835fae7bb 100644
--- a/jetty-core/jetty-io/src/main/java/org/eclipse/jetty/io/ByteBufferPool.java
+++ b/jetty-core/jetty-io/src/main/java/org/eclipse/jetty/io/ByteBufferPool.java
@@ -19,6 +19,7 @@ import java.util.List;
 import java.util.Objects;
 
 import org.eclipse.jetty.util.BufferUtil;
+import org.eclipse.jetty.util.IO;
 
 /**
  * <p>A pool for {@link RetainableByteBuffer} instances.</p>
@@ -136,7 +137,7 @@ public interface ByteBufferPool
         {
             super(Objects.requireNonNullElse(wrapped, NON_POOLING));
             _direct = direct;
-            _size = size >= 0 ? size : 8192;
+            _size = size >= 0 ? size : IO.DEFAULT_BUFFER_SIZE;
         }
 
         public boolean isDirect()
diff --git a/jetty-core/jetty-io/src/main/java/org/eclipse/jetty/io/RetainableByteBuffer.java b/jetty-core/jetty-io/src/main/java/org/eclipse/jetty/io/RetainableByteBuffer.java
index 4a25de06bbd..243975879eb 100644
--- a/jetty-core/jetty-io/src/main/java/org/eclipse/jetty/io/RetainableByteBuffer.java
+++ b/jetty-core/jetty-io/src/main/java/org/eclipse/jetty/io/RetainableByteBuffer.java
@@ -27,6 +27,7 @@ import java.util.Objects;
 import org.eclipse.jetty.util.Blocker;
 import org.eclipse.jetty.util.BufferUtil;
 import org.eclipse.jetty.util.Callback;
+import org.eclipse.jetty.util.IO;
 import org.eclipse.jetty.util.IteratingNestedCallback;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -1439,7 +1440,7 @@ public interface RetainableByteBuffer extends Retainable
          */
         public DynamicCapacity(ByteBufferPool pool, boolean direct, long maxSize, int aggregationSize, int minRetainSize)
         {
-            this(null, new ByteBufferPool.Sized(pool, direct, maxSize > 0 && maxSize < 8192L ? (int)maxSize : aggregationSize), maxSize, minRetainSize);
+            this(null, new ByteBufferPool.Sized(pool, direct, maxSize > 0 && maxSize < IO.DEFAULT_BUFFER_SIZE ? (int)maxSize : aggregationSize), maxSize, minRetainSize);
         }
 
         private DynamicCapacity(List<RetainableByteBuffer> buffers, ByteBufferPool.Sized pool, long maxSize, int minRetainSize)
@@ -1500,7 +1501,7 @@ public interface RetainableByteBuffer extends Retainable
                         throw new BufferOverflowException();
 
                     int length = (int)size;
-                    RetainableByteBuffer combined = _pool.acquire(length, _pool.isDirect());
+                    RetainableByteBuffer combined = _pool.acquire(length);
                     ByteBuffer byteBuffer = combined.getByteBuffer();
                     BufferUtil.flipToFill(byteBuffer);
                     for (RetainableByteBuffer buffer : _buffers)
@@ -2007,7 +2008,7 @@ public interface RetainableByteBuffer extends Retainable
                 aggregateSize = Math.max(length, aggregateSize);
                 if (aggregateSize > space)
                     aggregateSize = (int)space;
-                _aggregate = _pool.acquire(aggregateSize, _pool.isDirect()).asMutable();
+                _aggregate = _pool.acquire(aggregateSize, _pool.isDirect());
                 checkAggregateLimit(space);
                 _buffers.add(_aggregate);
             }
diff --git a/jetty-core/jetty-io/src/test/java/org/eclipse/jetty/io/BufferedContentSinkTest.java b/jetty-core/jetty-io/src/test/java/org/eclipse/jetty/io/BufferedContentSinkTest.java
index 6f86ab91b16..52382499211 100644
--- a/jetty-core/jetty-io/src/test/java/org/eclipse/jetty/io/BufferedContentSinkTest.java
+++ b/jetty-core/jetty-io/src/test/java/org/eclipse/jetty/io/BufferedContentSinkTest.java
@@ -32,6 +32,7 @@ import org.eclipse.jetty.io.content.AsyncContent;
 import org.eclipse.jetty.io.content.BufferedContentSink;
 import org.eclipse.jetty.util.BufferUtil;
 import org.eclipse.jetty.util.Callback;
+import org.eclipse.jetty.util.IO;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -257,7 +258,7 @@ public class BufferedContentSinkTest
 
         try (AsyncContent async = new AsyncContent(); )
         {
-            BufferedContentSink buffered = new BufferedContentSink(async, _bufferPool, false, 8192, 8192);
+            BufferedContentSink buffered = new BufferedContentSink(async, _bufferPool, false, IO.DEFAULT_BUFFER_SIZE, IO.DEFAULT_BUFFER_SIZE);
 
             Callback.Completable callback = new Callback.Completable();
             buffered.write(false, BufferUtil.toBuffer("Hello "), callback);
@@ -485,7 +486,7 @@ public class BufferedContentSinkTest
         try (AsyncContent async = new AsyncContent())
         {
             BufferedContentSink buffered = new BufferedContentSink(async, _bufferPool, true, 4096, 4096);
-            AtomicInteger count = new AtomicInteger(8192);
+            AtomicInteger count = new AtomicInteger(IO.DEFAULT_BUFFER_SIZE);
             CountDownLatch complete = new CountDownLatch(1);
             Callback callback = new Callback()
             {
@@ -571,7 +572,7 @@ public class BufferedContentSinkTest
         try (AsyncContent async = new AsyncContent())
         {
             BufferedContentSink buffered = new BufferedContentSink(async, _bufferPool, true, 1, 4096);
-            AtomicInteger count = new AtomicInteger(8192);
+            AtomicInteger count = new AtomicInteger(IO.DEFAULT_BUFFER_SIZE);
             CountDownLatch complete = new CountDownLatch(1);
             Callback callback = new Callback()
             {
diff --git a/jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/AbstractConnectionFactory.java b/jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/AbstractConnectionFactory.java
index 130324f1ef8..db5087b7927 100644
--- a/jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/AbstractConnectionFactory.java
+++ b/jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/AbstractConnectionFactory.java
@@ -19,6 +19,7 @@ import java.util.List;
 import org.eclipse.jetty.io.AbstractConnection;
 import org.eclipse.jetty.io.EndPoint;
 import org.eclipse.jetty.util.ArrayUtil;
+import org.eclipse.jetty.util.IO;
 import org.eclipse.jetty.util.annotation.ManagedAttribute;
 import org.eclipse.jetty.util.annotation.ManagedObject;
 import org.eclipse.jetty.util.component.ContainerLifeCycle;
@@ -32,7 +33,7 @@ public abstract class AbstractConnectionFactory extends ContainerLifeCycle imple
 {
     private final String _protocol;
     private final List<String> _protocols;
-    private int _inputBufferSize = 8192;
+    private int _inputBufferSize = IO.DEFAULT_BUFFER_SIZE;
 
     protected AbstractConnectionFactory(String protocol)
     {
diff --git a/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/BufferUtil.java b/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/BufferUtil.java
index e70c49fc780..8e672a6ce43 100644
--- a/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/BufferUtil.java
+++ b/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/BufferUtil.java
@@ -664,11 +664,11 @@ public class BufferUtil
 
     public static void readFrom(InputStream is, int needed, ByteBuffer buffer) throws IOException
     {
-        ByteBuffer tmp = allocate(8192);
+        ByteBuffer tmp = allocate(IO.DEFAULT_BUFFER_SIZE);
 
         while (needed > 0 && buffer.hasRemaining())
         {
-            int l = is.read(tmp.array(), 0, 8192);
+            int l = is.read(tmp.array(), 0, IO.DEFAULT_BUFFER_SIZE);
             if (l < 0)
                 break;
             tmp.position(0);
@@ -688,7 +688,7 @@ public class BufferUtil
         else
         {
             int totalRead = 0;
-            ByteBuffer tmp = allocate(8192);
+            ByteBuffer tmp = allocate(IO.DEFAULT_BUFFER_SIZE);
             while (BufferUtil.space(tmp) > 0 && BufferUtil.space(buffer) > 0)
             {
                 int read = is.read(tmp.array(), 0, Math.min(BufferUtil.space(tmp), BufferUtil.space(buffer)));
diff --git a/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/IO.java b/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/IO.java
index 9948480185a..5b78681da0c 100644
--- a/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/IO.java
+++ b/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/IO.java
@@ -57,6 +57,8 @@ public class IO
 {
     private static final Logger LOG = LoggerFactory.getLogger(IO.class);
 
+    public static final int DEFAULT_BUFFER_SIZE = 8192;
+
     public static final String
         CRLF = "\r\n";
 
diff --git a/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/UrlEncoded.java b/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/UrlEncoded.java
index 0164a4673bd..b83bd4780cc 100644
--- a/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/UrlEncoded.java
+++ b/jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/UrlEncoded.java
@@ -606,7 +606,7 @@ public class UrlEncoded
     public static void decodeUtf16To(InputStream in, BiConsumer<String, String> adder, int maxLength, int maxKeys) throws IOException
     {
         InputStreamReader input = new InputStreamReader(in, StandardCharsets.UTF_16);
-        StringWriter buf = new StringWriter(8192);
+        StringWriter buf = new StringWriter(IO.DEFAULT_BUFFER_SIZE);
         IO.copy(input, buf, maxLength);
 
         decodeTo(buf.getBuffer().toString(), adder, StandardCharsets.UTF_16, maxKeys);