diff --git a/frontend/src/app/main/refs.cljs b/frontend/src/app/main/refs.cljs
index 84f6bd72f2..bb7fc0392a 100644
--- a/frontend/src/app/main/refs.cljs
+++ b/frontend/src/app/main/refs.cljs
@@ -609,6 +609,8 @@
 
 (defn workspace-thumbnail-by-id
   [object-id]
+  ;; Resolving a media id builds a new map on each read; compare by
+  ;; value so subscribers do not re-render on every store change.
   (l/derived
    (fn [state]
      (when-let [entry (dm/get-in state [:thumbnails object-id])]
@@ -616,7 +618,8 @@
          (and (:uri entry)
               (not (resolved-uri? (:uri entry))))
          (update :uri cf/resolve-media))))
-   st/state))
+   st/state
+   =))
 
 (def workspace-text-modifier
   (l/derived :workspace-text-modifier st/state))
diff --git a/frontend/test/frontend_tests/main/refs_test.cljs b/frontend/test/frontend_tests/main/refs_test.cljs
index 99c9f57657..581ff949d2 100644
--- a/frontend/test/frontend_tests/main/refs_test.cljs
+++ b/frontend/test/frontend_tests/main/refs_test.cljs
@@ -8,6 +8,7 @@
   (:require
    [app.common.uuid :as uuid]
    [app.main.refs :as refs]
+   [app.main.store :as st]
    [cljs.test :as t :include-macros true]))
 
 (def ^:private resolved-uri? @#'refs/resolved-uri?)
@@ -28,3 +29,23 @@
   (t/is (false? (resolved-uri? (uuid/next))))
   (t/is (false? (resolved-uri? nil)))
   (t/is (false? (resolved-uri? 42))))
+
+(t/deftest thumbnail-ref-ignores-unrelated-state-changes
+  ;; A thumbnail loaded from the server keeps a media id as :uri, and
+  ;; the ref resolves it to a new map on each read. Subscribers (root
+  ;; frames, assets) must not re-render on every unrelated store change.
+  (let [object-id (str (uuid/next))
+        ref       (refs/workspace-thumbnail-by-id object-id)
+        calls     (atom 0)]
+    (swap! st/state assoc-in [:thumbnails object-id] {:uri (uuid/next) :rendered-at nil})
+    (add-watch ref ::probe (fn [_ _ _ _] (swap! calls inc)))
+    (try
+      (swap! st/state assoc ::probe (uuid/next))
+      (t/is (zero? @calls) "unrelated change does not notify")
+      (swap! st/state assoc-in [:thumbnails object-id :uri] (uuid/next))
+      (t/is (= 1 @calls) "a new thumbnail uri notifies")
+      (finally
+        (remove-watch ref ::probe)
+        (swap! st/state #(-> %
+                             (dissoc ::probe)
+                             (update :thumbnails dissoc object-id)))))))