diff --git a/crates/re_ui/src/lib.rs b/crates/re_ui/src/lib.rs
index d8a9d782db95..a985ba713820 100644
--- a/crates/re_ui/src/lib.rs
+++ b/crates/re_ui/src/lib.rs
@@ -195,16 +195,19 @@ impl ReUi {
         label: &str,
         value: &mut Num,
         range: RangeInclusive<Num>,
-    ) where
+    ) -> egui::Response
+    where
         Num: egui::emath::Numeric,
     {
         ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
-            ui.add_sized(
+            let response = ui.add_sized(
                 [Self::box_width(), Self::box_height()],
                 egui::DragValue::new(value).clamp_range(range),
             );
             ui.label(egui::RichText::new(label).color(self.design_tokens.gray_900));
-        });
+            response
+        })
+        .inner
     }
 
     pub fn labeled_toggle_switch(&self, ui: &mut egui::Ui, label: &str, value: &mut bool) {
diff --git a/crates/re_viewer/src/app.rs b/crates/re_viewer/src/app.rs
index 4c0e2d4023bc..35abd96480df 100644
--- a/crates/re_viewer/src/app.rs
+++ b/crates/re_viewer/src/app.rs
@@ -493,9 +493,12 @@ impl eframe::App for App {
             };
         }
 
-        if self.backend_handle.is_none() {
-            self.backend_handle = App::spawn_backend();
-        };
+        #[cfg(not(target_arch = "wasm32"))]
+        {
+            if self.backend_handle.is_none() {
+                self.backend_handle = App::spawn_backend();
+            };
+        }
 
         if self.startup_options.memory_limit.limit.is_none() {
             // we only warn about high memory usage if the user hasn't specified a limit
diff --git a/crates/re_viewer/src/ui/device_settings_panel.rs b/crates/re_viewer/src/ui/device_settings_panel.rs
index 19cd0b1e953b..a1f23aa387b4 100644
--- a/crates/re_viewer/src/ui/device_settings_panel.rs
+++ b/crates/re_viewer/src/ui/device_settings_panel.rs
@@ -152,20 +152,35 @@ impl DeviceSettingsPanel {
                                                     .selected_device
                                                     .supported_left_mono_resolutions
                                                 {
-                                                    ui.selectable_value(
-                                                        &mut device_config.left_camera.resolution,
-                                                        *res,
-                                                        format!("{res}"),
-                                                    );
+                                                    if ui
+                                                        .selectable_value(
+                                                            &mut device_config
+                                                                .left_camera
+                                                                .resolution,
+                                                            *res,
+                                                            format!("{res}"),
+                                                        )
+                                                        .changed()
+                                                    {
+                                                        device_config.right_camera.resolution =
+                                                            *res;
+                                                    }
                                                 }
                                             },
                                         );
-                                        ctx.re_ui.labeled_dragvalue(
-                                            ui,
-                                            "FPS",
-                                            &mut device_config.left_camera.fps,
-                                            0..=120,
-                                        );
+                                        if ctx
+                                            .re_ui
+                                            .labeled_dragvalue(
+                                                ui,
+                                                "FPS",
+                                                &mut device_config.left_camera.fps,
+                                                0..=120,
+                                            )
+                                            .changed()
+                                        {
+                                            device_config.right_camera.fps =
+                                                device_config.left_camera.fps;
+                                        }
                                         ctx.re_ui.labeled_checkbox(
                                             ui,
                                             "Stream",
@@ -191,20 +206,34 @@ impl DeviceSettingsPanel {
                                                     .selected_device
                                                     .supported_right_mono_resolutions
                                                 {
-                                                    ui.selectable_value(
-                                                        &mut device_config.right_camera.resolution,
-                                                        *res,
-                                                        format!("{res}"),
-                                                    );
+                                                    if ui
+                                                        .selectable_value(
+                                                            &mut device_config
+                                                                .right_camera
+                                                                .resolution,
+                                                            *res,
+                                                            format!("{res}"),
+                                                        )
+                                                        .changed()
+                                                    {
+                                                        device_config.left_camera.resolution = *res;
+                                                    }
                                                 }
                                             },
                                         );
-                                        ctx.re_ui.labeled_dragvalue(
-                                            ui,
-                                            "FPS",
-                                            &mut device_config.right_camera.fps,
-                                            0..=120,
-                                        );
+                                        if ctx
+                                            .re_ui
+                                            .labeled_dragvalue(
+                                                ui,
+                                                "FPS",
+                                                &mut device_config.right_camera.fps,
+                                                0..=120,
+                                            )
+                                            .changed()
+                                        {
+                                            device_config.left_camera.fps =
+                                                device_config.right_camera.fps;
+                                        }
                                         ctx.re_ui.labeled_checkbox(
                                             ui,
                                             "Stream",