diff --git a/bec_widgets/widgets/plots/waveform/curve.py b/bec_widgets/widgets/plots/waveform/curve.py
index 2cad459f..d539d185 100644
--- a/bec_widgets/widgets/plots/waveform/curve.py
+++ b/bec_widgets/widgets/plots/waveform/curve.py
@@ -97,6 +97,7 @@ class Curve(BECConnector, pg.PlotDataItem):
         self.apply_config()
         self.dap_params = None
         self.dap_summary = None
+        self.slice_index = None
         if kwargs:
             self.set(**kwargs)
 
@@ -303,14 +304,14 @@ class Curve(BECConnector, pg.PlotDataItem):
         self.apply_config()
         self.parent_item.update_with_scan_history(-1)
 
-    def get_data(self) -> tuple[np.ndarray, np.ndarray]:
+    def get_data(self) -> tuple[np.ndarray | None, np.ndarray | None]:
         """
         Get the data of the curve.
         Returns:
             tuple[np.ndarray,np.ndarray]: X and Y data of the curve.
         """
         try:
-            x_data, y_data = self.getData()
+            x_data, y_data = self.getOriginalDataset()
         except TypeError:
             x_data, y_data = np.array([]), np.array([])
         return x_data, y_data
diff --git a/bec_widgets/widgets/plots/waveform/waveform.py b/bec_widgets/widgets/plots/waveform/waveform.py
index 586775a3..16465e0e 100644
--- a/bec_widgets/widgets/plots/waveform/waveform.py
+++ b/bec_widgets/widgets/plots/waveform/waveform.py
@@ -134,6 +134,7 @@ class Waveform(PlotBase):
         # Curve data
         self._sync_curves = []
         self._async_curves = []
+        self._slice_index = None
         self._dap_curves = []
         self._mode: Literal["none", "sync", "async", "mixed"] = "none"
 
@@ -947,6 +948,7 @@ class Waveform(PlotBase):
             self.old_scan_id = self.scan_id
             self.scan_id = current_scan_id
             self.scan_item = self.queue.scan_storage.find_scan_by_ID(self.scan_id)  # live scan
+            self._slice_index = None  # Reset the slice index
 
             self._mode = self._categorise_device_curves()
 
@@ -1069,6 +1071,7 @@ class Waveform(PlotBase):
 
             # If there's actual data, set it
             if device_data is not None:
+                self._auto_adjust_async_curve_settings(curve, len(device_data))
                 if x_data is not None:
                     curve.setData(x_data, device_data)
                 else:
@@ -1107,16 +1110,18 @@ class Waveform(PlotBase):
             msg(dict): Message with the async data.
             metadata(dict): Metadata of the message.
         """
-        y_data = None
-        x_data = None
         instruction = metadata.get("async_update", {}).get("type")
         max_shape = metadata.get("async_update", {}).get("max_shape", [])
         for curve in self._async_curves:
+            new_data = None
+            y_data = None
+            x_data = None
             y_entry = curve.config.signal.entry
             x_name = self.x_axis_mode["name"]
             for device, async_data in msg["signals"].items():
                 if device == y_entry:
                     data_plot = async_data["value"]
+                    # Add
                     if instruction == "add":
                         if len(max_shape) > 1:
                             if len(data_plot.shape) > 1:
@@ -1134,17 +1139,70 @@ class Waveform(PlotBase):
                             else:
                                 x_data = async_data["timestamp"]
                                 # FIXME x axis wrong if timestamp switched during scan
-                            curve.setData(x_data, new_data)
-                        else:  # this means index as x
-                            curve.setData(new_data)
+                    # Add slice
+                    elif instruction == "add_slice":
+                        current_slice_id = metadata.get("async_update", {}).get("index")
+                        data_plot = async_data["value"]
+                        if current_slice_id != curve.slice_index:
+                            curve.slice_index = current_slice_id
+                        else:
+                            x_data, y_data = curve.get_data()
+                        if y_data is not None:
+                            new_data = np.hstack((y_data, data_plot))
+                        else:
+                            new_data = data_plot
+                    # Replace
                     elif instruction == "replace":
                         if x_name == "timestamp":
                             x_data = async_data["timestamp"]
-                            curve.setData(x_data, data_plot)
-                        else:
-                            curve.setData(data_plot)
+                        new_data = data_plot
+
+                    # If update is not add, add_slice or replace, continue.
+                    if new_data is None:
+                        continue
+                    # Hide symbol, activate downsampling if data >1000
+                    self._auto_adjust_async_curve_settings(curve, len(new_data))
+                    # Set data on the curve
+                    if x_name == "timestamp" and instruction != "add_slice":
+                        curve.setData(x_data, new_data)
+                    else:
+                        curve.setData(np.linspace(0, len(new_data) - 1, len(new_data)), new_data)
+
         self.request_dap_update.emit()
 
+    def _auto_adjust_async_curve_settings(
+        self,
+        curve: Curve,
+        data_length: int,
+        limit: int = 1000,
+        method: Literal["subsample", "mean", "peak"] | None = "mean",
+    ) -> None:
+        """
+        Based on the length of the data this method will adjust the plotting settings of
+        Curve items, by deactivating the symbol and activating downsampling auto, method='mean',
+        if the data length exceeds N points. If the data length is less than N points, the
+        symbol will be activated and downsampling will be deactivated. Maximum points will be
+        5x the limit.
+
+        Args:
+            curve(Curve): The curve to adjust.
+            data_length(int): The length of the data.
+            limit(int): The limit of the data length to activate the downsampling.
+
+        """
+        if limit <= 1:
+            logger.warning("Limit must be greater than 1.")
+            return
+        if data_length > limit:
+            if curve.config.symbol is not None:
+                curve.set_symbol(None)
+            sampling_factor = int(data_length / (5 * limit))  # increase by limit 5x
+            curve.setDownsampling(ds=sampling_factor, auto=None, method=method)
+        elif data_length <= limit:
+            curve.set_symbol("o")
+            sampling_factor = 1
+            curve.setDownsampling(ds=sampling_factor, auto=None, method=method)
+
     def setup_dap_for_scan(self):
         """Setup DAP updates for the new scan."""
         self.bec_dispatcher.disconnect_slot(
diff --git a/tests/unit_tests/test_waveform_next_gen.py b/tests/unit_tests/test_waveform_next_gen.py
index 3883f8e7..caf97697 100644
--- a/tests/unit_tests/test_waveform_next_gen.py
+++ b/tests/unit_tests/test_waveform_next_gen.py
@@ -529,16 +529,14 @@ def test_setup_async_curve(qtbot, mocked_client, monkeypatch):
 
 
 @pytest.mark.parametrize("x_mode", ("timestamp", "index"))
-def test_on_async_readback(qtbot, mocked_client, x_mode):
+def test_on_async_readback_add_update(qtbot, mocked_client, x_mode):
     """
     Test that on_async_readback extends or replaces async data depending on metadata instruction.
     For 'timestamp' mode, new timestamps are appended to x_data.
     For 'index' mode, x_data simply increases by integer index.
     """
     wf = create_widget(qtbot, Waveform, client=mocked_client)
-    dummy_scan = create_dummy_scan_item()
-    wf.scan_item = dummy_scan
-
+    wf.scan_item = create_dummy_scan_item()
     c = wf.plot(arg1="async_device", label="async_device-async_device")
     wf._async_curves = [c]
     # Suppose existing data
@@ -547,7 +545,8 @@ def test_on_async_readback(qtbot, mocked_client, x_mode):
     # Set the x_axis_mode
     wf.x_axis_mode["name"] = x_mode
 
-    # Extend readback
+    ############# Test add ################
+
     msg = {"signals": {"async_device": {"value": [100, 200], "timestamp": [1001, 1002]}}}
     metadata = {"async_update": {"max_shape": [None], "type": "add"}}
     wf.on_async_readback(msg, metadata)
@@ -575,6 +574,72 @@ def test_on_async_readback(qtbot, mocked_client, x_mode):
 
     np.testing.assert_array_equal(y_data2, [999])
 
+    ############# Test add_slice ################
+
+    # Few updates, no downsampling, no symbol removed
+    waveform_shape = 10
+    for ii in range(10):
+        msg = {"signals": {"async_device": {"value": [100], "timestamp": [1001]}}}
+        metadata = {
+            "async_update": {"max_shape": [None, waveform_shape], "index": 0, "type": "add_slice"}
+        }
+        wf.on_async_readback(msg, metadata)
+
+    # Old data should be deleted since the slice_index did not match
+    x_data, y_data = c.get_data()
+    assert len(y_data) == 10
+    assert len(x_data) == 10
+    assert c.opts["symbol"] == "o"
+
+    # Clear data from curve
+    c.setData([], [])
+
+    # Test large updates, limit 1000 to deactivate symbols, downsampling for 8000 should be factor 2.
+    waveform_shape = 12000
+    for ii in range(12):
+        msg = {
+            "signals": {
+                "async_device": {
+                    "value": np.array(range(1000)),
+                    "timestamp": (ii + 1) * np.linspace(0, 1000 - 1, 1000),
+                }
+            }
+        }
+        metadata = {
+            "async_update": {"max_shape": [None, waveform_shape], "index": 0, "type": "add_slice"}
+        }
+        wf.on_async_readback(msg, metadata)
+    x_data, y_data = c.get_data()
+    assert len(y_data) == waveform_shape
+    assert len(x_data) == waveform_shape
+    assert c.opts["symbol"] == None
+    # Get displayed data
+    displayed_x, displayed_y = c.getData()
+    assert len(displayed_y) == waveform_shape / 2
+    assert len(displayed_x) == waveform_shape / 2
+    assert displayed_x[-1] == waveform_shape - 1  # Should be the correct index stil.
+
+    ############# Test replace ################
+    waveform_shape = 10
+    for ii in range(10):
+        msg = {
+            "signals": {
+                "async_device": {
+                    "value": np.array(range(waveform_shape)),
+                    "timestamp": np.array(range(waveform_shape)),
+                }
+            }
+        }
+        metadata = {"async_update": {"type": "replace"}}
+        wf.on_async_readback(msg, metadata)
+
+    x_data, y_data = c.get_data()
+    assert np.array_equal(y_data, np.array(range(waveform_shape)))
+    assert len(x_data) == waveform_shape
+    assert c.opts["symbol"] == "o"
+    y_displayed, x_displayed = c.getData()
+    assert len(y_displayed) == waveform_shape
+
 
 def test_get_x_data(qtbot, mocked_client, monkeypatch):
     """