diff --git a/frontend/src/app/main/ui/workspace/viewport/actions.cljs b/frontend/src/app/main/ui/workspace/viewport/actions.cljs
index c5e6992015..ec228d5de7 100644
--- a/frontend/src/app/main/ui/workspace/viewport/actions.cljs
+++ b/frontend/src/app/main/ui/workspace/viewport/actions.cljs
@@ -443,6 +443,14 @@
     (mf/use-fn
      (fn [event]
        (drag-debug-bump-move!)
+       ;; FIXME(pan-end-debug): log first 3 pointer-moves of any drag so we
+       ;; can distinguish "user paused" (no moves arriving) from "freeze
+       ;; in the chain" (moves arriving but set-view-box delayed).
+       (let [n (.-moveCount drag-debug-state)]
+         (when (<= n 3)
+           (js/console.log
+            "[drag-debug] pointer-move #" n
+            "@" (.-timeStamp event) "ms (timestamp)")))
        (let [raw-pt   (dom/get-client-position event)
              pt       (uwvv/point->viewport raw-pt)
 
diff --git a/frontend/src/app/render_wasm/api.cljs b/frontend/src/app/render_wasm/api.cljs
index 62ae893dda..478eca4f7f 100644
--- a/frontend/src/app/render_wasm/api.cljs
+++ b/frontend/src/app/render_wasm/api.cljs
@@ -1133,6 +1133,10 @@
 ;; Fire the deferred full render the moment the gesture ends. We watch the
 ;; store rather than coupling viewport.cljs to api.cljs (which would risk a
 ;; circular dep) — render-wasm already depends on app.main.store.
+;; FIXME(pan-end-debug): timestamp of the most recent gesture start, used
+;; only to measure gesture-start latency. Remove with rest of pan-end debug.
+(defonce ^:private _gesture-start-ts (atom nil))
+
 (defonce ^:private _gesture-end-watcher
   (add-watch st/state
              ::gesture-end-watcher
@@ -1145,6 +1149,12 @@
                      now-active? (or (:panning new-ws)
                                      (:zooming new-ws)
                                      (some? (:transform new-ws)))]
+                 (when (and (not was-active?) now-active?)
+                   ;; FIXME(pan-end-debug): remove with rest of pan-end debug instrumentation
+                   (reset! _gesture-start-ts (js/performance.now))
+                   (js/console.log
+                    "[pan-end-debug] gesture STARTED -> ts="
+                    @_gesture-start-ts))
                  (when (and was-active? (not now-active?))
                    ;; FIXME(pan-end-debug): remove with rest of pan-end debug instrumentation
                    (js/console.log "[pan-end-debug] gesture ended -> flushing render")
@@ -1153,16 +1163,25 @@
 (defn set-view-box
   [zoom vbox]
   ;; FIXME(pan-end-debug): remove with rest of pan-end debug instrumentation
-  (js/console.log "[pan-end-debug] set-view-box CALLED (vbox:" (:x vbox) (:y vbox) ")")
-  (perf/begin-measure "set-view-box")
-  (h/call wasm/internal-module "_set_view_start")
-  (h/call wasm/internal-module "_set_view" zoom (- (:x vbox)) (- (:y vbox)))
-  (perf/end-measure "set-view-box")
-
-  (perf/begin-measure "render-from-cache")
-  (h/call wasm/internal-module "_render_from_cache" 0)
-  (render-finish)
-  (perf/end-measure "render-from-cache"))
+  (let [t0 (js/performance.now)
+        start-ts @_gesture-start-ts
+        delta-from-start (when start-ts (- t0 start-ts))]
+    (perf/begin-measure "set-view-box")
+    (h/call wasm/internal-module "_set_view_start")
+    (h/call wasm/internal-module "_set_view" zoom (- (:x vbox)) (- (:y vbox)))
+    (perf/end-measure "set-view-box")
+    (let [t1 (js/performance.now)]
+      (perf/begin-measure "render-from-cache")
+      (h/call wasm/internal-module "_render_from_cache" 0)
+      (render-finish)
+      (perf/end-measure "render-from-cache")
+      (let [t2 (js/performance.now)]
+        (js/console.log
+         "[pan-end-debug] set-view-box CALLED"
+         "Δfromstart=" (if delta-from-start (str (.toFixed delta-from-start 1) "ms") "n/a")
+         "viewStart+set=" (str (.toFixed (- t1 t0) 2) "ms")
+         "renderFromCache=" (str (.toFixed (- t2 t1) 2) "ms")
+         "TOTAL=" (str (.toFixed (- t2 t0) 2) "ms"))))))
 
 (defn- ensure-text-content
   "Guarantee that the shape always sends a valid text tree to WASM. When the
diff --git a/render-wasm/src/main.rs b/render-wasm/src/main.rs
index 2f5d7ef175..09278b71ec 100644
--- a/render-wasm/src/main.rs
+++ b/render-wasm/src/main.rs
@@ -428,8 +428,19 @@ pub extern "C" fn set_view_start() -> Result<()> {
         VIEW_INTERACTION_START = performance::get_time();
     }
     performance::begin_measure!("set_view_start");
-    get_render_state().options.set_fast_mode(true);
+    let render_state = get_render_state();
+    render_state.options.set_fast_mode(true);
+    // Cancel any in-flight async full-quality render from the previous
+    // gesture. Without this, an `_render 0` started at the previous
+    // gesture-end keeps eating rAFs and eventually runs
+    // `post_full_render_block` mid-gesture, blocking the main thread for
+    // tens to hundreds of ms — visible as a "freeze" right after the new
+    // gesture starts.  Symmetric with `set_view_end`, which already does
+    // this on the way out.
+    render_state.cancel_animation_frame();
     performance::end_measure!("set_view_start");
+    // FIXME(pan-end-debug): remove with rest of pan-end debug instrumentation
+    println!("[pan-end-debug] set_view_start: cancelled in-flight render (if any)");
     Ok(())
 }