diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 0081fb82..6776cb76 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -10,10 +10,8 @@ repos:
         hooks:
               - id: flake8
                 name: flake8 (code linting)
-                language_version: python3.9
       - repo: https://github.com/psf/black
         rev: 22.12.0  # New version tags can be found here: https://github.com/psf/black/tags
         hooks:
               - id: black
                 name: black (code formatting)
-                language_version: python3.9
diff --git a/timely_beliefs/beliefs/classes.py b/timely_beliefs/beliefs/classes.py
index 69484cc9..c21c4268 100644
--- a/timely_beliefs/beliefs/classes.py
+++ b/timely_beliefs/beliefs/classes.py
@@ -398,6 +398,36 @@ def search_session(  # noqa: C901
             get_bounds=True,
         )
 
+        def apply_event_timing_filters(q):
+            """Apply filters that concern the event time.
+
+            This includes any custom filters
+            """
+            if not pd.isnull(event_starts_after):
+                q = q.filter(cls.event_start >= event_starts_after)
+            if not pd.isnull(event_ends_after):
+                if sensor.event_resolution == timedelta(0):
+                    # inclusive
+                    q = q.filter(cls.event_start >= event_ends_after)
+                else:
+                    # exclusive
+                    q = q.filter(
+                        cls.event_start > event_ends_after - sensor.event_resolution
+                    )
+            if not pd.isnull(event_starts_before):
+                if sensor.event_resolution == timedelta(0):
+                    # inclusive
+                    q = q.filter(cls.event_start <= event_starts_before)
+                else:
+                    # exclusive
+                    q = q.filter(cls.event_start < event_starts_before)
+            if not pd.isnull(event_ends_before):
+                q = q.filter(
+                    cls.event_start <= event_ends_before - sensor.event_resolution
+                )
+
+            return q
+
         def apply_belief_timing_filters(q):
             """Apply filters that concern the belief timing.
 
@@ -411,8 +441,8 @@ def apply_belief_timing_filters(q):
                 knowledge_horizon_min, timedelta.min
             ):
                 q = q.filter(
-                    cls.event_start
-                    >= beliefs_after + cls.belief_horizon + knowledge_horizon_min
+                    cls.event_start - cls.belief_horizon
+                    >= beliefs_after + knowledge_horizon_min
                 )
             if not pd.isnull(
                 beliefs_before
@@ -420,8 +450,8 @@ def apply_belief_timing_filters(q):
                 knowledge_horizon_max, timedelta.max
             ):
                 q = q.filter(
-                    cls.event_start
-                    <= beliefs_before + cls.belief_horizon + knowledge_horizon_max
+                    cls.event_start - cls.belief_horizon
+                    <= beliefs_before + knowledge_horizon_max
                 )
 
             # Apply belief horizon filter
@@ -448,28 +478,7 @@ def apply_belief_timing_filters(q):
             cls.event_value,
         ).filter(cls.sensor_id == sensor.id)
 
-        # Apply event time filter
-        if not pd.isnull(event_starts_after):
-            q = q.filter(cls.event_start >= event_starts_after)
-        if not pd.isnull(event_ends_after):
-            if sensor.event_resolution == timedelta(0):
-                # inclusive
-                q = q.filter(cls.event_start >= event_ends_after)
-            else:
-                # exclusive
-                q = q.filter(
-                    cls.event_start + sensor.event_resolution > event_ends_after
-                )
-        if not pd.isnull(event_starts_before):
-            if sensor.event_resolution == timedelta(0):
-                # inclusive
-                q = q.filter(cls.event_start <= event_starts_before)
-            else:
-                # exclusive
-                q = q.filter(cls.event_start < event_starts_before)
-        if not pd.isnull(event_ends_before):
-            q = q.filter(cls.event_start + sensor.event_resolution <= event_ends_before)
-
+        q = apply_event_timing_filters(q)
         q = apply_belief_timing_filters(q)
 
         # Apply source filter
@@ -477,7 +486,7 @@ def apply_belief_timing_filters(q):
             sources: list = [source] if not isinstance(source, list) else source
             q = q.join(source_class).filter(cls.source_id.in_([s.id for s in sources]))
 
-        # Apply most recent beliefs filter
+        # Apply most recent beliefs filter as subquery
         most_recent_beliefs_only_incompatible_criteria = (
             beliefs_before is not None or beliefs_after is not None
         ) and sensor.knowledge_horizon_fnc not in (ex_ante.__name__, ex_post.__name__)
@@ -490,10 +499,12 @@ def apply_belief_timing_filters(q):
                 cls.source_id,
                 func.min(cls.belief_horizon).label("most_recent_belief_horizon"),
             )
-            # Apply belief timing filters to the subquery, too, before taking the minimum horizon
+            # Apply event and belief timing filters to the subquery, too,
+            # before taking the minimum horizon (the former is crucial for speed)
+            subq = apply_event_timing_filters(subq)
+            subq = apply_belief_timing_filters(subq)
             subq = (
-                apply_belief_timing_filters(subq)
-                .filter(cls.sensor_id == sensor.id)
+                subq.filter(cls.sensor_id == sensor.id)
                 .group_by(cls.event_start, cls.source_id)
                 .subquery()
             )
@@ -506,7 +517,7 @@ def apply_belief_timing_filters(q):
                 ),
             )
 
-        # Apply most recent events filter
+        # Apply most recent events filter as subquery
         if most_recent_events_only:
             subq_most_recent_events = (
                 select(