diff --git a/lib/pleroma/bbs/handler.ex b/lib/pleroma/bbs/handler.ex
index 106fe5d18..f34be961f 100644
--- a/lib/pleroma/bbs/handler.ex
+++ b/lib/pleroma/bbs/handler.ex
@@ -95,7 +95,6 @@ defmodule Pleroma.BBS.Handler do
     activities =
       [user.ap_id | user.following]
       |> ActivityPub.fetch_activities(params)
-      |> ActivityPub.contain_timeline(user)
 
     Enum.each(activities, fn activity ->
       puts_activity(activity)
diff --git a/lib/pleroma/filter.ex b/lib/pleroma/filter.ex
index 79efc29f0..90457dadf 100644
--- a/lib/pleroma/filter.ex
+++ b/lib/pleroma/filter.ex
@@ -38,7 +38,8 @@ defmodule Pleroma.Filter do
     query =
       from(
         f in Pleroma.Filter,
-        where: f.user_id == ^user_id
+        where: f.user_id == ^user_id,
+        order_by: [desc: :id]
       )
 
     Repo.all(query)
diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index 233fee4fa..7cd5b889b 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -540,8 +540,6 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
             )
         )
 
-      Ecto.Adapters.SQL.to_sql(:all, Repo, query)
-
       query
     else
       Logger.error("Could not restrict visibility to #{visibility}")
@@ -557,8 +555,6 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
           fragment("activity_visibility(?, ?, ?) = ?", a.actor, a.recipients, a.data, ^visibility)
       )
 
-    Ecto.Adapters.SQL.to_sql(:all, Repo, query)
-
     query
   end
 
@@ -569,6 +565,18 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
 
   defp restrict_visibility(query, _visibility), do: query
 
+  defp restrict_thread_visibility(query, %{"user" => %User{ap_id: ap_id}}) do
+    query =
+      from(
+        a in query,
+        where: fragment("thread_visibility(?, (?)->>'id') = true", ^ap_id, a.data)
+      )
+
+    query
+  end
+
+  defp restrict_thread_visibility(query, _), do: query
+
   def fetch_user_activities(user, reading_user, params \\ %{}) do
     params =
       params
@@ -848,6 +856,7 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
     |> restrict_muted(opts)
     |> restrict_media(opts)
     |> restrict_visibility(opts)
+    |> restrict_thread_visibility(opts)
     |> restrict_replies(opts)
     |> restrict_reblogs(opts)
     |> restrict_pinned(opts)
@@ -965,12 +974,4 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
   def contain_activity(%Activity{} = activity, %User{} = user) do
     contain_broken_threads(activity, user)
   end
-
-  # do post-processing on a timeline
-  def contain_timeline(timeline, user) do
-    timeline
-    |> Enum.filter(fn activity ->
-      contain_activity(activity, user)
-    end)
-  end
 end
diff --git a/lib/pleroma/web/activity_pub/visibility.ex b/lib/pleroma/web/activity_pub/visibility.ex
index b38ee0442..46dd46575 100644
--- a/lib/pleroma/web/activity_pub/visibility.ex
+++ b/lib/pleroma/web/activity_pub/visibility.ex
@@ -1,6 +1,7 @@
 defmodule Pleroma.Web.ActivityPub.Visibility do
   alias Pleroma.Activity
   alias Pleroma.Object
+  alias Pleroma.Repo
   alias Pleroma.User
 
   def is_public?(%Object{data: %{"type" => "Tombstone"}}), do: false
@@ -38,25 +39,14 @@ defmodule Pleroma.Web.ActivityPub.Visibility do
     visible_for_user?(activity, nil) || Enum.any?(x, &(&1 in y))
   end
 
-  # guard
-  def entire_thread_visible_for_user?(nil, _user), do: false
+  def entire_thread_visible_for_user?(%Activity{} = activity, %User{} = user) do
+    {:ok, %{rows: [[result]]}} =
+      Ecto.Adapters.SQL.query(Repo, "SELECT thread_visibility($1, $2)", [
+        user.ap_id,
+        activity.data["id"]
+      ])
 
-  # XXX: Probably even more inefficient than the previous implementation intended to be a placeholder untill https://git.pleroma.social/pleroma/pleroma/merge_requests/971 is in develop
-  # credo:disable-for-previous-line Credo.Check.Readability.MaxLineLength
-
-  def entire_thread_visible_for_user?(
-        %Activity{} = tail,
-        # %Activity{data: %{"object" => %{"inReplyTo" => parent_id}}} = tail,
-        user
-      ) do
-    case Object.normalize(tail) do
-      %{data: %{"inReplyTo" => parent_id}} when is_binary(parent_id) ->
-        parent = Activity.get_in_reply_to_activity(tail)
-        visible_for_user?(tail, user) && entire_thread_visible_for_user?(parent, user)
-
-      _ ->
-        visible_for_user?(tail, user)
-    end
+    result
   end
 
   def get_visibility(object) do
diff --git a/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex b/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex
index 87e597074..66056a846 100644
--- a/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex
+++ b/lib/pleroma/web/mastodon_api/mastodon_api_controller.ex
@@ -303,7 +303,6 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIController do
     activities =
       [user.ap_id | user.following]
       |> ActivityPub.fetch_activities(params)
-      |> ActivityPub.contain_timeline(user)
       |> Enum.reverse()
 
     conn
diff --git a/lib/pleroma/web/twitter_api/twitter_api_controller.ex b/lib/pleroma/web/twitter_api/twitter_api_controller.ex
index 3c5a70be9..31e86685a 100644
--- a/lib/pleroma/web/twitter_api/twitter_api_controller.ex
+++ b/lib/pleroma/web/twitter_api/twitter_api_controller.ex
@@ -101,9 +101,7 @@ defmodule Pleroma.Web.TwitterAPI.Controller do
       |> Map.put("blocking_user", user)
       |> Map.put("user", user)
 
-    activities =
-      ActivityPub.fetch_activities([user.ap_id | user.following], params)
-      |> ActivityPub.contain_timeline(user)
+    activities = ActivityPub.fetch_activities([user.ap_id | user.following], params)
 
     conn
     |> put_view(ActivityView)
diff --git a/priv/repo/migrations/20190515222404_add_thread_visibility_function.exs b/priv/repo/migrations/20190515222404_add_thread_visibility_function.exs
new file mode 100644
index 000000000..dc9abc998
--- /dev/null
+++ b/priv/repo/migrations/20190515222404_add_thread_visibility_function.exs
@@ -0,0 +1,73 @@
+defmodule Pleroma.Repo.Migrations.AddThreadVisibilityFunction do
+  use Ecto.Migration
+  @disable_ddl_transaction true
+
+  def up do
+    statement = """
+    CREATE OR REPLACE FUNCTION thread_visibility(actor varchar, activity_id varchar) RETURNS boolean AS $$
+    DECLARE
+      public varchar := 'https://www.w3.org/ns/activitystreams#Public';
+      child objects%ROWTYPE;
+      activity activities%ROWTYPE;
+      actor_user users%ROWTYPE;
+      author_fa varchar;
+      valid_recipients varchar[];
+    BEGIN
+      --- Fetch our actor.
+      SELECT * INTO actor_user FROM users WHERE users.ap_id = actor;
+
+      --- Fetch our initial activity.
+      SELECT * INTO activity FROM activities WHERE activities.data->>'id' = activity_id;
+
+      LOOP
+        --- Ensure that we have an activity before continuing.
+        --- If we don't, the thread is not satisfiable.
+        IF activity IS NULL THEN
+          RETURN false;
+        END IF;
+
+        --- We only care about Create activities.
+        IF activity.data->>'type' != 'Create' THEN
+          RETURN true;
+        END IF;
+
+        --- Normalize the child object into child.
+        SELECT * INTO child FROM objects
+        INNER JOIN activities ON COALESCE(activities.data->'object'->>'id', activities.data->>'object') = objects.data->>'id'
+        WHERE COALESCE(activity.data->'object'->>'id', activity.data->>'object') = objects.data->>'id';
+
+        --- Fetch the author's AS2 following collection.
+        SELECT COALESCE(users.follower_address, '') INTO author_fa FROM users WHERE users.ap_id = activity.actor;
+
+        --- Prepare valid recipients array.
+        valid_recipients := ARRAY[actor, public];
+        IF ARRAY[author_fa] && actor_user.following THEN
+          valid_recipients := valid_recipients || author_fa;
+        END IF;
+
+        --- Check visibility.
+        IF NOT valid_recipients && activity.recipients THEN
+          --- activity not visible, break out of the loop
+          RETURN false;
+        END IF;
+
+        --- If there's a parent, load it and do this all over again.
+        IF (child.data->'inReplyTo' IS NOT NULL) AND (child.data->'inReplyTo' != 'null'::jsonb) THEN
+          SELECT * INTO activity FROM activities
+          INNER JOIN objects ON COALESCE(activities.data->'object'->>'id', activities.data->>'object') = objects.data->>'id'
+          WHERE child.data->>'inReplyTo' = objects.data->>'id';
+        ELSE
+          RETURN true;
+        END IF;
+      END LOOP;
+    END;
+    $$ LANGUAGE plpgsql IMMUTABLE;
+    """
+
+    execute(statement)
+  end
+
+  def down do
+    execute("drop function thread_visibility(actor varchar, activity_id varchar)")
+  end
+end
diff --git a/test/user_test.exs b/test/user_test.exs
index f256396c0..16a014f2f 100644
--- a/test/user_test.exs
+++ b/test/user_test.exs
@@ -873,7 +873,6 @@ defmodule Pleroma.UserTest do
 
       assert [activity] ==
                ActivityPub.fetch_activities([user2.ap_id | user2.following], %{"user" => user2})
-               |> ActivityPub.contain_timeline(user2)
 
       {:ok, _user} = User.deactivate(user)
 
@@ -882,7 +881,6 @@ defmodule Pleroma.UserTest do
 
       assert [] ==
                ActivityPub.fetch_activities([user2.ap_id | user2.following], %{"user" => user2})
-               |> ActivityPub.contain_timeline(user2)
     end
   end
 
diff --git a/test/web/activity_pub/activity_pub_test.exs b/test/web/activity_pub/activity_pub_test.exs
index 0f90aa1ac..34e23b852 100644
--- a/test/web/activity_pub/activity_pub_test.exs
+++ b/test/web/activity_pub/activity_pub_test.exs
@@ -960,17 +960,21 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubTest do
           "in_reply_to_status_id" => private_activity_2.id
         })
 
-      activities = ActivityPub.fetch_activities([user1.ap_id | user1.following])
+      activities =
+        ActivityPub.fetch_activities([user1.ap_id | user1.following])
+        |> Enum.map(fn a -> a.id end)
 
       private_activity_1 = Activity.get_by_ap_id_with_object(private_activity_1.data["id"])
 
-      assert [public_activity, private_activity_1, private_activity_3] == activities
+      assert [public_activity.id, private_activity_1.id, private_activity_3.id] == activities
 
       assert length(activities) == 3
 
-      activities = ActivityPub.contain_timeline(activities, user1)
+      activities =
+        ActivityPub.fetch_activities([user1.ap_id | user1.following], %{"user" => user1})
+        |> Enum.map(fn a -> a.id end)
 
-      assert [public_activity, private_activity_1] == activities
+      assert [public_activity.id, private_activity_1.id] == activities
       assert length(activities) == 2
     end
   end