diff --git a/superset/models/core.py b/superset/models/core.py
index 2996625e2cbf..68c305f227bc 100644
--- a/superset/models/core.py
+++ b/superset/models/core.py
@@ -248,12 +248,17 @@ def get_viz(self):
         )
 
     @classmethod
-    def import_obj(cls, slc_to_import, import_time=None):
+    def import_obj(cls, slc_to_import, slc_to_override, import_time=None):
         """Inserts or overrides slc in the database.
 
         remote_id and import_time fields in params_dict are set to track the
         slice origin and ensure correct overrides for multiple imports.
         Slice.perm is used to find the datasources and connect them.
+
+        :param Slice slc_to_import: Slice object to import
+        :param Slice slc_to_override: Slice to replace, id matches remote_id
+        :returns: The resulting id for the imported slice
+        :rtype: int
         """
         session = db.session
         make_transient(slc_to_import)
@@ -261,13 +266,6 @@ def import_obj(cls, slc_to_import, import_time=None):
         slc_to_import.alter_params(
             remote_id=slc_to_import.id, import_time=import_time)
 
-        # find if the slice was already imported
-        slc_to_override = None
-        for slc in session.query(Slice).all():
-            if ('remote_id' in slc.params_dict and
-                    slc.params_dict['remote_id'] == slc_to_import.id):
-                slc_to_override = slc
-
         slc_to_import = slc_to_import.copy()
         params = slc_to_import.params_dict
         slc_to_import.datasource_id = ConnectorRegistry.get_datasource_by_name(
@@ -432,10 +430,16 @@ def alter_positions(dashboard, old_to_new_slc_id_dict):
         new_timed_refresh_immune_slices = []
         new_expanded_slices = {}
         i_params_dict = dashboard_to_import.params_dict
+        remote_id_slice_map = {
+            slc.params_dict['remote_id']: slc
+            for slc in session.query(Slice).all()
+            if 'remote_id' in slc.params_dict
+        }
         for slc in slices:
             logging.info('Importing slice {} from the dashboard: {}'.format(
                 slc.to_json(), dashboard_to_import.dashboard_title))
-            new_slc_id = Slice.import_obj(slc, import_time=import_time)
+            remote_slc = remote_id_slice_map.get(slc.id)
+            new_slc_id = Slice.import_obj(slc, remote_slc, import_time=import_time)
             old_to_new_slc_id_dict[slc.id] = new_slc_id
             # update json metadata that deals with slice ids
             new_slc_id_str = '{}'.format(new_slc_id)