diff --git a/src/java/com/threerings/presents/client/BlockingCommunicator.java b/src/java/com/threerings/presents/client/BlockingCommunicator.java
index e842318f2..a9904076f 100644
--- a/src/java/com/threerings/presents/client/BlockingCommunicator.java
+++ b/src/java/com/threerings/presents/client/BlockingCommunicator.java
@@ -757,6 +757,7 @@ public class BlockingCommunicator extends Communicator
 
             // create and register the channel
             _datagramChannel = DatagramChannel.open();
+            _datagramChannel.socket().setTrafficClass(0x10); // IPTOS_LOWDELAY
             _datagramChannel.configureBlocking(false);
             _datagramChannel.register(_selector, SelectionKey.OP_READ, null);
 
diff --git a/src/java/com/threerings/presents/server/net/ConnectionManager.java b/src/java/com/threerings/presents/server/net/ConnectionManager.java
index 1192d740f..e75f1dc2c 100644
--- a/src/java/com/threerings/presents/server/net/ConnectionManager.java
+++ b/src/java/com/threerings/presents/server/net/ConnectionManager.java
@@ -403,6 +403,7 @@ public class ConnectionManager extends LoopingThread
             try {
                 // create a channel and add it to the select set
                 _datagramChannel = DatagramChannel.open();
+                _datagramChannel.socket().setTrafficClass(0x10); // IPTOS_LOWDELAY
                 _datagramChannel.configureBlocking(false);
                 InetSocketAddress isa = getAddress(port);
                 _datagramChannel.socket().bind(isa);