diff --git a/client/lib/snowflake.go b/client/lib/snowflake.go
index 7442ce9..77c784e 100644
--- a/client/lib/snowflake.go
+++ b/client/lib/snowflake.go
@@ -32,6 +32,7 @@ import (
 	"math/rand"
 	"net"
 	"net/url"
+	"os"
 	"strings"
 	"time"
 
@@ -385,6 +386,14 @@ func newSession(snowflakes SnowflakeCollector) (net.PacketConn, *smux.Session, e
 		0, // default resend
 		1, // nc=1 => congestion window off
 	)
+	if os.Getenv("SNOWFLAKE_TEST_KCP_FAST3MODE") == "1" {
+		conn.SetNoDelay(
+			1,
+			10,
+			2,
+			1,
+		)
+	}
 	// On the KCP connection we overlay an smux session and stream.
 	smuxConfig := smux.DefaultConfig()
 	smuxConfig.Version = 2
diff --git a/server/lib/snowflake.go b/server/lib/snowflake.go
index d7d0c40..b158f03 100644
--- a/server/lib/snowflake.go
+++ b/server/lib/snowflake.go
@@ -41,6 +41,7 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"os"
 	"sync"
 	"time"
 
@@ -265,6 +266,14 @@ func (l *SnowflakeListener) acceptSessions(ln *kcp.Listener) error {
 			0, // default resend
 			1, // nc=1 => congestion window off
 		)
+		if os.Getenv("SNOWFLAKE_TEST_KCP_FAST3MODE") == "1" {
+			conn.SetNoDelay(
+				1,
+				10,
+				2,
+				1,
+			)
+		}
 		go func() {
 			defer conn.Close()
 			err := l.acceptStreams(conn)