diff --git a/h2mux/h2mux_test.go b/h2mux/h2mux_test.go
index 5f6b8b5b..97312047 100644
--- a/h2mux/h2mux_test.go
+++ b/h2mux/h2mux_test.go
@@ -15,10 +15,11 @@ import (
 	"testing"
 	"time"
 
-	"github.com/cloudflare/cloudflared/logger"
 	"github.com/pkg/errors"
 	"github.com/stretchr/testify/assert"
 	"golang.org/x/sync/errgroup"
+
+	"github.com/cloudflare/cloudflared/logger"
 )
 
 const (
@@ -1032,3 +1033,108 @@ func openStreams(b *testing.B, muxPair *DefaultMuxerPair, n int) {
 	}
 	assert.NoError(b, errGroup.Wait())
 }
+
+func BenchmarkSingleStreamLargeResponseBody(b *testing.B) {
+	const bodySize = 1 << 24
+
+	const writeBufferSize = 16 << 10
+	const writeN = bodySize / writeBufferSize
+	payload := make([]byte, writeBufferSize)
+	for i := range payload {
+		payload[i] = byte(i % 256)
+	}
+
+	const readBufferSize = 16 << 10
+	const readN = bodySize / readBufferSize
+	responseBody := make([]byte, readBufferSize)
+
+	f := MuxedStreamFunc(func(stream *MuxedStream) error {
+		if len(stream.Headers) != 1 {
+			b.Fatalf("expected %d headers, got %d", 1, len(stream.Headers))
+		}
+		if stream.Headers[0].Name != "test-header" {
+			b.Fatalf("expected header name %s, got %s", "test-header", stream.Headers[0].Name)
+		}
+		if stream.Headers[0].Value != "headerValue" {
+			b.Fatalf("expected header value %s, got %s", "headerValue", stream.Headers[0].Value)
+		}
+		stream.WriteHeaders([]Header{
+			{Name: "response-header", Value: "responseValue"},
+		})
+		for i := 0; i < writeN; i++ {
+			n, err := stream.Write(payload)
+			if err != nil {
+				b.Fatalf("origin write error: %s", err)
+			}
+			if n != len(payload) {
+				b.Fatalf("origin short write: %d/%d bytes", n, len(payload))
+			}
+		}
+
+		return nil
+	})
+
+	name := fmt.Sprintf("%s_%d", b.Name(), rand.Int())
+	origin, edge := net.Pipe()
+
+	muxPair := &DefaultMuxerPair{
+		OriginMuxConfig: MuxerConfig{
+			Timeout:                 testHandshakeTimeout,
+			Handler:                 f,
+			IsClient:                true,
+			Name:                    "origin",
+			Logger:                  logger.NewOutputWriter(logger.NewMockWriteManager()),
+			DefaultWindowSize:       defaultWindowSize,
+			MaxWindowSize:           maxWindowSize,
+			StreamWriteBufferMaxLen: defaultWriteBufferMaxLen,
+			HeartbeatInterval:       defaultTimeout,
+			MaxHeartbeats:           defaultRetries,
+		},
+		OriginConn: origin,
+		EdgeMuxConfig: MuxerConfig{
+			Timeout:                 testHandshakeTimeout,
+			IsClient:                false,
+			Name:                    "edge",
+			Logger:                  logger.NewOutputWriter(logger.NewMockWriteManager()),
+			DefaultWindowSize:       defaultWindowSize,
+			MaxWindowSize:           maxWindowSize,
+			StreamWriteBufferMaxLen: defaultWriteBufferMaxLen,
+			HeartbeatInterval:       defaultTimeout,
+			MaxHeartbeats:           defaultRetries,
+		},
+		EdgeConn: edge,
+		doneC:    make(chan struct{}),
+	}
+	assert.NoError(b, muxPair.Handshake(name))
+	muxPair.Serve(b)
+
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		stream, err := muxPair.OpenEdgeMuxStream(
+			[]Header{{Name: "test-header", Value: "headerValue"}},
+			nil,
+		)
+		if err != nil {
+			b.Fatalf("error in OpenStream: %s", err)
+		}
+		if len(stream.Headers) != 1 {
+			b.Fatalf("expected %d headers, got %d", 1, len(stream.Headers))
+		}
+		if stream.Headers[0].Name != "response-header" {
+			b.Fatalf("expected header name %s, got %s", "response-header", stream.Headers[0].Name)
+		}
+		if stream.Headers[0].Value != "responseValue" {
+			b.Fatalf("expected header value %s, got %s", "responseValue", stream.Headers[0].Value)
+		}
+
+		for k := 0; k < readN; k++ {
+			n, err := io.ReadFull(stream, responseBody)
+			if err != nil {
+				b.Fatalf("error from (*MuxedStream).Read: %s", err)
+			}
+			if n != len(responseBody) {
+				b.Fatalf("expected response body to have %d bytes, got %d", len(responseBody), n)
+			}
+		}
+	}
+}