diff --git a/extensions/core/src/main/java/io/quarkiverse/cxf/transport/generated/AppendBuffer.java b/extensions/core/src/main/java/io/quarkiverse/cxf/transport/generated/AppendBuffer.java
index c90dbb24c..49b68cc89 100644
--- a/extensions/core/src/main/java/io/quarkiverse/cxf/transport/generated/AppendBuffer.java
+++ b/extensions/core/src/main/java/io/quarkiverse/cxf/transport/generated/AppendBuffer.java
@@ -1,10 +1,15 @@
 package io.quarkiverse.cxf.transport.generated;
 
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
 import java.util.ArrayDeque;
 import java.util.Objects;
 import io.netty.buffer.ByteBuf;
-import io.netty.buffer.ByteBufAllocator;
 import io.netty.buffer.CompositeByteBuf;
+import io.netty.buffer.PooledByteBufAllocator;
+import io.netty.util.internal.PlatformDependent;
+import io.vertx.core.buffer.impl.VertxByteBufAllocator;
 
 /**
  * Adapted by sync-quarkus-classes.groovy from
@@ -19,7 +24,26 @@
  */
 final class AppendBuffer {
 
-    private final ByteBufAllocator allocator;
+    private static final MethodHandle virtualMh = PlatformDependent.javaVersion() >= 21 ? findVirtualMH() : null;
+
+    private static MethodHandle findVirtualMH() {
+        try {
+            return MethodHandles.publicLookup().findVirtual(Thread.class, "isVirtual", MethodType.methodType(boolean.class));
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    private static boolean isVirtualThread() {
+        if (virtualMh == null) {
+            return false;
+        }
+        try {
+            return (boolean) virtualMh.invokeExact(Thread.currentThread());
+        } catch (Throwable t) {
+            return false;
+        }
+    }
 
     private final int minChunkSize;
 
@@ -31,25 +55,27 @@ final class AppendBuffer {
 
     private int size;
 
-    private AppendBuffer(ByteBufAllocator allocator, int minChunkSize, int capacity) {
-        this.allocator = allocator;
+    private boolean anyHeap;
+
+    private AppendBuffer(int minChunkSize, int capacity) {
         this.minChunkSize = Math.min(minChunkSize, capacity);
         this.capacity = capacity;
+        this.anyHeap = false;
     }
 
     /**
      * This buffer append data in a single eagerly allocated {@link ByteBuf}.
      */
-    public static AppendBuffer eager(ByteBufAllocator allocator, int capacity) {
-        return new AppendBuffer(allocator, capacity, capacity);
+    public static AppendBuffer eager(int capacity) {
+        return new AppendBuffer(capacity, capacity);
     }
 
     /**
      * This buffer append data in multiples {@link ByteBuf}s sized as each {@code len} in {@link #append}.<br>
      * The data is consolidated in a single {@link CompositeByteBuf} on {@link #clear}.
      */
-    public static AppendBuffer exact(ByteBufAllocator allocator, int capacity) {
-        return new AppendBuffer(allocator, 0, capacity);
+    public static AppendBuffer exact(int capacity) {
+        return new AppendBuffer(0, capacity);
     }
 
     /**
@@ -57,8 +83,8 @@ public static AppendBuffer exact(ByteBufAllocator allocator, int capacity) {
      * as each {@code len}, if greater than it.<br>
      * The data is consolidated in a single {@link CompositeByteBuf} on {@link #clear}.
      */
-    public static AppendBuffer withMinChunks(ByteBufAllocator allocator, int minChunkSize, int capacity) {
-        return new AppendBuffer(allocator, minChunkSize, capacity);
+    public static AppendBuffer withMinChunks(int minChunkSize, int capacity) {
+        return new AppendBuffer(minChunkSize, capacity);
     }
 
     private ByteBuf lastBuffer() {
@@ -111,7 +137,14 @@ public int append(byte[] bytes, int off, int len) {
         } else {
             chunkCapacity = toWrite;
         }
-        var tmpBuf = allocator.directBuffer(chunkCapacity);
+        boolean isVirtualThread = isVirtualThread();
+        final ByteBuf tmpBuf;
+        if (isVirtualThread) {
+            // VertxByteBufAllocator allocates cheaper heap buffers ie which doesn't use reference counting
+            tmpBuf = VertxByteBufAllocator.DEFAULT.heapBuffer(chunkCapacity);
+        } else {
+            tmpBuf = PooledByteBufAllocator.DEFAULT.directBuffer(chunkCapacity);
+        }
         try {
             tmpBuf.writeBytes(bytes, off, toWrite);
         } catch (Throwable t) {
@@ -133,6 +166,9 @@ public int append(byte[] bytes, int off, int len) {
                 throw t;
             }
         }
+        if (isVirtualThread) {
+            anyHeap = true;
+        }
         size += toWrite;
         return toWrite + alreadyWritten;
     }
@@ -159,6 +195,7 @@ public ByteBuf clear() {
         if (others == null || others.isEmpty()) {
             size = 0;
             buffer = null;
+            anyHeap = false;
             // super fast-path
             return firstBuf;
         }
@@ -168,10 +205,17 @@ public ByteBuf clear() {
     private CompositeByteBuf clearBuffers() {
         var firstBuf = buffer;
         var others = otherBuffers;
-        var batch = allocator.compositeDirectBuffer(1 + others.size());
+        CompositeByteBuf batch;
+        if (anyHeap) {
+            batch = new CompositeByteBuf(VertxByteBufAllocator.UNPOOLED_ALLOCATOR, false, 1 + others.size());
+        } else {
+            // This should be the allocator picked by Netty
+            batch = PooledByteBufAllocator.DEFAULT.compositeBuffer(1 + others.size());
+        }
         try {
             buffer = null;
             size = 0;
+            anyHeap = false;
             batch.addComponent(true, 0, firstBuf);
             for (int i = 0, othersCount = others.size(); i < othersCount; i++) {
                 // if addComponent fail, it takes care of releasing curr and throwing the exception:
diff --git a/extensions/core/src/main/java/io/quarkiverse/cxf/transport/generated/VertxServletOutputStream.java b/extensions/core/src/main/java/io/quarkiverse/cxf/transport/generated/VertxServletOutputStream.java
index d5d58c2a2..29d4d1f7f 100644
--- a/extensions/core/src/main/java/io/quarkiverse/cxf/transport/generated/VertxServletOutputStream.java
+++ b/extensions/core/src/main/java/io/quarkiverse/cxf/transport/generated/VertxServletOutputStream.java
@@ -7,7 +7,6 @@
 import jakarta.servlet.WriteListener;
 import org.jboss.logging.Logger;
 import io.netty.buffer.ByteBuf;
-import io.netty.buffer.PooledByteBufAllocator;
 import io.netty.handler.codec.http.HttpHeaderNames;
 import io.quarkiverse.cxf.transport.VertxReactiveRequestContext;
 import io.quarkus.vertx.core.runtime.VertxBufferImpl;
@@ -50,7 +49,7 @@ public class VertxServletOutputStream extends ServletOutputStream {
     public VertxServletOutputStream(VertxReactiveRequestContext context) {
         this.context = context;
         this.request = context.getContext().request();
-        this.appendBuffer = AppendBuffer.withMinChunks(PooledByteBufAllocator.DEFAULT, context.getDeployment().getResteasyReactiveConfig().getMinChunkSize(), context.getDeployment().getResteasyReactiveConfig().getOutputBufferSize());
+        this.appendBuffer = AppendBuffer.withMinChunks(context.getDeployment().getResteasyReactiveConfig().getMinChunkSize(), context.getDeployment().getResteasyReactiveConfig().getOutputBufferSize());
         request.response().exceptionHandler(new Handler<Throwable>() {
 
             @Override