diff --git a/history.txt b/history.txt
index d039a4c80f..903f062a24 100644
--- a/history.txt
+++ b/history.txt
@@ -2,6 +2,7 @@
  * Installer (ticket #1864):
    - Fix wrapper selection on Windows 10
    - Add support for IzPack 5
+ * SSU: Sync/notify improvements (ticket #2260)
 
 2018-07-08 zzz
  * i2psnark: Add comment icon (ticket #2278)
diff --git a/router/java/src/net/i2p/router/RouterVersion.java b/router/java/src/net/i2p/router/RouterVersion.java
index a6204817e3..f2522cd4ed 100644
--- a/router/java/src/net/i2p/router/RouterVersion.java
+++ b/router/java/src/net/i2p/router/RouterVersion.java
@@ -18,7 +18,7 @@ public class RouterVersion {
     /** deprecated */
     public final static String ID = "Monotone";
     public final static String VERSION = CoreVersion.VERSION;
-    public final static long BUILD = 8;
+    public final static long BUILD = 9;
 
     /** for example "-test" */
     public final static String EXTRA = "";
diff --git a/router/java/src/net/i2p/router/transport/udp/InboundMessageFragments.java b/router/java/src/net/i2p/router/transport/udp/InboundMessageFragments.java
index 592936768f..27819055df 100644
--- a/router/java/src/net/i2p/router/transport/udp/InboundMessageFragments.java
+++ b/router/java/src/net/i2p/router/transport/udp/InboundMessageFragments.java
@@ -260,7 +260,7 @@ class InboundMessageFragments /*implements UDPTransport.PartialACKSource */{
         // By calling add(), this also is a failsafe against possible
         // races in OutboundMessageFragments.
         if (newAck && from.getOutboundMessageCount() > 0)
-            _outbound.add(from);
+            _outbound.add(from, 0);
 
         return rv;
     }
diff --git a/router/java/src/net/i2p/router/transport/udp/OutboundMessageFragments.java b/router/java/src/net/i2p/router/transport/udp/OutboundMessageFragments.java
index 10e7989993..8f605d8dc5 100644
--- a/router/java/src/net/i2p/router/transport/udp/OutboundMessageFragments.java
+++ b/router/java/src/net/i2p/router/transport/udp/OutboundMessageFragments.java
@@ -51,11 +51,6 @@ class OutboundMessageFragments {
      */
     private Iterator<PeerState> _iterator;
 
-    /**
-     *  Avoid sync in add() if possible (not 100% reliable)
-     */
-    private volatile boolean _isWaiting;
-
     private volatile boolean _alive;
     private final PacketBuilder _builder;
 
@@ -104,7 +99,7 @@ class OutboundMessageFragments {
         _alive = false;
         _activePeers.clear();
         synchronized (_activePeers) {
-            _activePeers.notifyAll();
+            _activePeers.notify();
         }
     }
 
@@ -165,7 +160,7 @@ class OutboundMessageFragments {
             // will throw IAE if peer == null
             OutboundMessageState state = new OutboundMessageState(_context, msg, peer);
             peer.add(state);
-            add(peer);
+            add(peer, state.fragmentSize(0));
         } catch (IllegalArgumentException iae) {
             _transport.failed(msg, "Peer disconnected quickly");
             return;
@@ -182,7 +177,7 @@ class OutboundMessageFragments {
         if (peer == null)
             throw new RuntimeException("null peer for " + state);
         peer.add(state);
-        add(peer);
+        add(peer, state.fragmentSize(0));
         //_context.statManager().addRateData("udp.outboundActiveCount", active, 0);
     }
 
@@ -195,10 +190,15 @@ class OutboundMessageFragments {
         if (peer == null)
             throw new RuntimeException("null peer");
         int sz = states.size();
+        int min = peer.fragmentSize();
         for (int i = 0; i < sz; i++) {
-            peer.add(states.get(i));
+            OutboundMessageState state = states.get(i);
+            peer.add(state);
+            int fsz = state.fragmentSize(0);
+            if (fsz < min)
+                min = fsz;
         }
-        add(peer);
+        add(peer, min);
         //_context.statManager().addRateData("udp.outboundActiveCount", active, 0);
     }
 
@@ -211,10 +211,10 @@ class OutboundMessageFragments {
      * There are larger chances of adding the PeerState "behind" where
      * the iterator is now... but these issues are the same as before concurrentification.
      *
+     * @param the minimum size we can send, or 0 to always notify
      * @since 0.8.9
      */
-    public void add(PeerState peer) {
-        boolean wasEmpty = _activePeers.isEmpty();
+    public void add(PeerState peer, int size) {
         boolean added = _activePeers.add(peer);
         if (added) {
             if (_log.shouldLog(Log.DEBUG))
@@ -229,9 +229,9 @@ class OutboundMessageFragments {
         // no, this doesn't always work.
         // Also note that the iterator in getNextVolley may have alreay passed us,
         // or not reflect the addition.
-        if (_isWaiting || wasEmpty) {
+        if (added || size <= 0 || peer.getSendWindowBytesRemaining() >= size) {
             synchronized (_activePeers) {
-                _activePeers.notifyAll();
+                _activePeers.notify();
             }
         }
     }
@@ -321,7 +321,6 @@ class OutboundMessageFragments {
                     // if we've gone all the way through the loop, wait
                     // ... unless nextSendDelay says we have more ready now
                     if (states == null && peersProcessed >= _activePeers.size() && nextSendDelay > 0) {
-                        _isWaiting = true;
                         peersProcessed = 0;
                         // why? we do this in the loop one at a time
                         //finishMessages();
@@ -341,7 +340,6 @@ class OutboundMessageFragments {
                                      _log.debug("Woken up while waiting");
                             }
                         }
-                        _isWaiting = false;
                     //} else {
                     //    if (_log.shouldLog(Log.DEBUG))
                     //        _log.debug("dont wait: alive=" + _alive + " state = " + state);