diff --git a/mantidimaging/gui/windows/live_viewer/model.py b/mantidimaging/gui/windows/live_viewer/model.py
index 92aa9620d26..0d15134a224 100644
--- a/mantidimaging/gui/windows/live_viewer/model.py
+++ b/mantidimaging/gui/windows/live_viewer/model.py
@@ -45,9 +45,9 @@ class ImageCache:
     image_list: list[Image_Data]
     image_paths: set[str] = set()
     max_cache_size: int | None = None
-    buffer_size: int | None = None
+    buffer_size: int = 10
 
-    def __init__(self, max_cache_size=None, buffer_size=None):
+    def __init__(self, max_cache_size=None, buffer_size=10):
         self.max_cache_size = max_cache_size
         self.buffer_size = buffer_size
 
@@ -62,10 +62,13 @@ def remove_from_cache(self, image: Image_Data):
         if image.image_path in self.cache_dict.keys():
             del self.cache_dict[image.image_path]
 
-    def remove_oldest_image(self):
+    def get_oldest_image(self):
         ordered_times = sorted(self.get_cached_image_modified_times())
         oldest_image_path = [path for path in self.cache_dict if self.cache_dict[path][1] == ordered_times[0]][0]
-        del self.cache_dict[oldest_image_path]
+        return oldest_image_path
+
+    def remove_oldest_image(self):
+        del self.cache_dict[self.get_oldest_image()]
 
     def load_image(self, image: Image_Data) -> np.ndarray:
         if image.image_path in self.cache_dict.keys():
@@ -85,34 +88,12 @@ def get_cached_image_paths(self):
         return list(self.cache_dict.keys())
 
     def get_cached_image_arrays(self):
-        print(f"{[info[0] for info in list(self.cache_dict.values())]=}")
         return np.stack([info[0] for info in list(self.cache_dict.values())])
 
     def get_cached_image_modified_times(self):
         return [info[1] for info in list(self.cache_dict.values())]
 
 
-    # def calc_mean_buffer(self):
-    #     nanInds = np.argwhere(np.isnan(self.mean))
-    #     left, top, right, bottom = self.roi
-    #     if nanInds.size > 0:
-    #         print(f"{self.mean=}")
-    #         if nanInds.size < self.buffer_size:
-    #             buffer_start = 0
-    #         else:
-    #             buffer_start = nanInds.size - self.buffer_size
-    #         dask_mean = dask.optimize(
-    #             dask.array.mean(self.delayed_stack[buffer_start:nanInds.size, top:bottom, left:right],
-    #                             axis=(1, 2)))[0].compute()
-    #         np.put(self.mean, range(buffer_start, nanInds.size), dask_mean)
-
-    def delete_all_data(self):
-        pass
-
-    def add_param_to_calc(self, param_name: str):
-        self.param_to_calc.append(param_name)
-
-
 class Image_Data:
     """
     Image Data Class to store represent image data.
@@ -205,7 +186,7 @@ def __init__(self, presenter: LiveViewerWindowPresenter):
         self.mean: np.ndarray = np.empty(0)
         self.mean_dict: dict[Path, float] = {}
         self.roi: SensibleROI | None = None
-        self.image_cache = ImageCache()
+        self.image_cache = ImageCache(max_cache_size=10)
         self.mean_cached: np.ndarray = np.empty(0)
 
     @property
@@ -291,6 +272,23 @@ def clear_and_update_mean_cache(self) -> None:
         self.calc_mean_cache()
         self.update_mean_with_cached_images()
 
+    def calc_mean_buffer(self):
+        nanInds = np.argwhere(np.isnan(self.mean))
+        if self.roi:
+            left, top, right, bottom = self.roi
+        else:
+            left, top, right, bottom = (0, 0, -1, -1)
+        if nanInds.size > 0:
+            oldest_image_modified_time = self.image_cache.cache_dict[self.image_cache.get_oldest_image()][1]
+            all_modified_times = [image.image_modified_time for image in self.images]
+            norm_mod_times = [mod_time - oldest_image_modified_time for mod_time in all_modified_times]
+            oldest_image_index = norm_mod_times.index(0.0)
+            for ind in range(len(nanInds) - 1, len(nanInds) - 1 - self.image_cache.buffer_size, -1):
+                if ind < 0:
+                    break
+                buffer_mean = np.mean(load_image_from_path(self.images[ind].image_path)[top:bottom, left:right])
+                np.put(self.mean, ind, buffer_mean)
+
 
 class ImageWatcher(QObject):
     """
diff --git a/mantidimaging/gui/windows/live_viewer/presenter.py b/mantidimaging/gui/windows/live_viewer/presenter.py
index cb91b6eae83..d5a907c8d5d 100644
--- a/mantidimaging/gui/windows/live_viewer/presenter.py
+++ b/mantidimaging/gui/windows/live_viewer/presenter.py
@@ -118,6 +118,7 @@ def display_image(self, image_data_obj: Image_Data) -> None:
             self.model.add_mean(image_data_obj, image_data)
         self.model.calc_mean_cache()
         self.model.update_mean_with_cached_images()
+        self.model.calc_mean_buffer()
         self.view.show_most_recent_image(image_data)
         self.update_spectrum(self.model.mean)
         self.view.live_viewer.show_error(None)
@@ -169,7 +170,7 @@ def handle_roi_moved(self, force_new_spectrums: bool = False):
         roi = self.view.live_viewer.get_roi()
         self.model.set_roi(roi)
         self.model.clear_mean()
-        self.model.calc_mean_fully()
+        self.model.clear_and_update_mean_cache()
         self.update_spectrum(self.model.mean)
 
     def handle_roi_moved_start(self):