diff --git a/client/packages/core/src/Reactor.js b/client/packages/core/src/Reactor.js
index 4bde34e3..0a98a670 100644
--- a/client/packages/core/src/Reactor.js
+++ b/client/packages/core/src/Reactor.js
@@ -13,7 +13,7 @@ import { buildPresenceSlice, hasPresenceResponseChanged } from "./presence";
 import { Deferred } from "./utils/Deferred";
 import { PersistedObject } from "./utils/PersistedObject";
 import { extractTriples } from "./model/instaqlResult";
-import { areObjectsDeepEqual } from "./utils/object";
+import { areObjectsDeepEqual, assocIn } from "./utils/object";
 import { createLinkIndex } from "./utils/linkIndex";
 import version from "./version";
 
@@ -460,7 +460,11 @@ export default class Reactor {
         break;
       case "refresh-presence":
         const roomId = msg["room-id"];
-        this._setPresencePeers(roomId, msg.data);
+        if (msg["edits"]) {
+          this._updatePresencePeers(roomId, msg["edits"]);
+        } else {
+          this._setPresencePeers(roomId, msg["data"]);
+        }
         this._notifyPresenceSubs(roomId);
         break;
       case "server-broadcast":
@@ -1676,6 +1680,23 @@ export default class Reactor {
     handler.cb(slice);
   }
 
+  _updatePresencePeers(roomId, edits) {
+    const peers = this._presence[roomId]?.result?.peers || {};
+    let sessions = Object.fromEntries(
+      Object.entries(peers).map(([k, v]) => [k, {data: v}]),
+    );
+    sessions[this._sessionId] = {data: this._presence[roomId]?.result?.user};
+    for (let [path, op, value] of edits) {
+      console.log('edit', path, op, value);
+      if (op === '+' || op === 'r') {
+        sessions = assocIn(sessions, path, value);
+      }
+      // TODO op === '-'
+    }
+
+    this._setPresencePeers(roomId, sessions);
+  }
+
   _setPresencePeers(roomId, data) {
     const sessions = { ...data };
     // no need to keep track of `user`
@@ -1684,9 +1705,7 @@ export default class Reactor {
       Object.entries(sessions).map(([k, v]) => [k, v.data]),
     );
 
-    this._presence[roomId] = this._presence[roomId] || {};
-    this._presence[roomId].result = this._presence[roomId].result || {};
-    this._presence[roomId].result.peers = peers;
+    this._presence = assocIn(this._presence, [roomId, 'result', 'peers'], peers);
   }
 
   // --------
diff --git a/client/packages/core/src/utils/object.js b/client/packages/core/src/utils/object.js
index 39c1ebcd..dff75f17 100644
--- a/client/packages/core/src/utils/object.js
+++ b/client/packages/core/src/utils/object.js
@@ -81,3 +81,21 @@ export function immutableDeepReplace(target, replaceValue, replacementValue) {
 export function isObject(val) {
   return typeof val === "object" && val !== null && !Array.isArray(val);
 }
+
+export function assocIn(obj, path, value) {
+  if (path.length === 0) {
+    return value;
+  }
+
+  let current = obj || {};
+  for (let i = 0; i < path.length - 1; i++) {
+    const key = path[i];
+    if (!(key in current) || typeof current[key] !== 'object') {
+      current[key] = typeof path[i + 1] === 'number' ? [] : {};
+    }
+    current = current[key];
+  }
+
+  current[path[path.length - 1]] = value;
+  return obj;
+}
diff --git a/server/deps.edn b/server/deps.edn
index 7f7e0a82..14a6e3f6 100644
--- a/server/deps.edn
+++ b/server/deps.edn
@@ -24,6 +24,7 @@
         org.slf4j/slf4j-api {:mvn/version "2.0.13"}
         cider/cider-nrepl {:mvn/version "0.45.0"}
         amazonica/amazonica {:mvn/version "0.3.167"}
+        juji/editscript {:mvn/version "0.6.4"}
 
         org.bouncycastle/bcprov-jdk15on {:mvn/version "1.70"}
         incanter/incanter {:mvn/version "1.9.3"
diff --git a/server/src/instant/reactive/ephemeral.clj b/server/src/instant/reactive/ephemeral.clj
index 30de8455..e177d048 100644
--- a/server/src/instant/reactive/ephemeral.clj
+++ b/server/src/instant/reactive/ephemeral.clj
@@ -4,6 +4,7 @@
    [clojure.core.async :as a]
    [clojure.set :as set]
    [datascript.core :refer [squuid-time-millis]]
+   [editscript.core :as editscript]
    [instant.config :as config]
    [instant.flags :as flags]
    [instant.gauges :as gauges]
@@ -31,7 +32,6 @@
 ;; Setup
 
 (declare room-refresh-ch)
-(defonce refresh-map-ch (a/chan 1024))
 ;; Channel we use to keep the hazelcast maps in sync for
 ;; apps that aren't using hazelcast. This can go away when
 ;; we fully migrate to hazelcast
@@ -49,7 +49,7 @@
 
 (defn init-hz [store-conn]
   (-> (java.util.logging.Logger/getLogger "com.hazelcast.system.logo")
-    (.setLevel java.util.logging.Level/WARNING))
+      (.setLevel java.util.logging.Level/WARNING))
   (System/setProperty "hazelcast.shutdownhook.enabled" "false")
   (let [config (Config.)
         network-config (.getNetworkConfig config)
@@ -176,43 +176,20 @@
 ;; ---------
 ;; Hazelcast
 
-(defn handle-refresh-event [store-conn room-key room-id]
-  (let [room-data (.get (get-hz-rooms-map) room-key)
-        session-ids (filter (fn [sess-id]
-                              (rs/get-session @store-conn sess-id))
-                            (keys room-data))]
-    (doseq [sess-id session-ids
-            :let [q (:receive-q (rs/get-socket @store-conn sess-id))]
-            :when q]
-      (receive-queue/enqueue->receive-q q
-                                        {:op :refresh-presence
-                                         :app-id (:app-id room-key)
-                                         :room-id room-id
-                                         :data room-data
-                                         :session-id sess-id}))))
-
-(defn straight-jacket-refresh-event!
-  [store-conn {:keys [room-key room-id on-sent]}]
-  (try
-    (handle-refresh-event store-conn room-key room-id)
-    (catch Throwable t
-      (tracer/record-exception-span! t {:name "rooms-refresh-map/straight-jacket"}))
-    (finally (on-sent))))
-
-(defn start-refresh-map-worker [store-conn ch]
-  (loop [event (a/<!! ch)]
-    (if (nil? event)
-      (tracer/record-info! {:name "room-refresh-map/closed"})
-      (do
-        (straight-jacket-refresh-event! store-conn event)
-        (recur (a/<!! ch))))))
+(def last-sent-state
+  (atom {}))
 
 (defn handle-event [store-conn ^DataAwareEntryEvent event]
   (let [{:keys [app-id room-id] :as room-key} (.getKey event)]
     (when (flags/use-hazelcast? app-id)
       (when (seq (get-in @room-maps [:rooms room-key :session-ids]))
-        (let [room-data (.get (get-hz-rooms-map) room-key)]
-          (doseq [sess-id (keys room-data)
+        (let [room-data      (.get (get-hz-rooms-map) room-key)
+              prev-room-data (get @last-sent-state room-key)
+              edits          (when prev-room-data
+                               (editscript/get-edits
+                                (editscript/diff prev-room-data room-data {:algo :a-star :str-diff :none})))]
+          (swap! last-sent-state assoc room-key room-data)
+          (doseq [[sess-id _] room-data
                   :let [q (:receive-q (rs/get-socket @store-conn sess-id))]
                   :when q]
             (receive-queue/enqueue->receive-q q
@@ -220,6 +197,7 @@
                                                :app-id app-id
                                                :room-id room-id
                                                :data room-data
+                                               :edits edits
                                                :session-id sess-id})))))))
 
 (defn handle-broadcast-message
@@ -408,7 +386,7 @@
 (defn refresh-rooms! [store-conn old-v new-v]
   (let [old-apps-rooms (get-in old-v [:rooms])
         new-apps-rooms (get-in new-v [:rooms])
-        changed-rooms (get-changed-rooms old-apps-rooms new-apps-rooms)]
+        changed-rooms  (get-changed-rooms old-apps-rooms new-apps-rooms)]
     (when (seq changed-rooms)
       (tracer/with-span! {:name "refresh-rooms"
                           :attributes {:room-ids (pr-str (map first changed-rooms))}}
@@ -470,7 +448,6 @@
 
 (defn stop []
   (a/close! room-refresh-ch)
-  (a/close! refresh-map-ch)
   (when-let [q ^LinkedBlockingQueue @hz-ops-q]
     (.put q close-sentinel))
   (reset! hz-ops-q nil)
@@ -481,3 +458,9 @@
 (defn restart []
   (stop)
   (start))
+
+(defn before-ns-unload []
+  (stop))
+
+(defn after-ns-reload []
+  (start))
diff --git a/server/src/instant/reactive/session.clj b/server/src/instant/reactive/session.clj
index cd72df7d..9b5fa3de 100644
--- a/server/src/instant/reactive/session.clj
+++ b/server/src/instant/reactive/session.clj
@@ -316,10 +316,12 @@
                                                :client-event-id client-event-id})))
 
 (defn- handle-refresh-presence!
-  [store-conn sess-id {:keys [app-id room-id data]}]
+  [store-conn sess-id {:keys [app-id room-id data edits]}]
   (rs/send-event! store-conn app-id sess-id {:op :refresh-presence
                                              :room-id room-id
-                                             :data data}))
+                                             :data (when (nil? edits)
+                                                     data)
+                                             :edits edits}))
 
 (defn- handle-client-broadcast!
   "Broadcasts a client message to other sessions in the room"