diff --git a/app/models/post.rb b/app/models/post.rb
index 0d6252e19..b13e2d780 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -251,8 +251,23 @@ class Post < ActiveRecord::Base
     order('sort_order desc, post_number desc')
   end
 
-  def self.summary
-    where(["(post_number = 1) or (percent_rank <= ?)", SiteSetting.summary_percent_filter.to_f / 100.0]).limit(SiteSetting.summary_max_results)
+  def self.summary(topic_id=nil)
+    # PERF: if you pass in nil it is WAY slower
+    #  pg chokes getting a reasonable plan
+    topic_id = topic_id ? topic_id.to_i : "posts.topic_id"
+
+    # percent rank has tons of ties
+    where(["post_number = 1 or id in (
+            SELECT p1.id
+            FROM posts p1
+            WHERE p1.percent_rank <= ? AND
+               p1.topic_id = #{topic_id}
+            ORDER BY p1.percent_rank
+            LIMIT ?
+          )",
+           SiteSetting.summary_percent_filter.to_f / 100.0,
+           SiteSetting.summary_max_results
+    ])
   end
 
   def update_flagged_posts_count
diff --git a/lib/topic_view.rb b/lib/topic_view.rb
index 6a440eade..b9ffd6434 100644
--- a/lib/topic_view.rb
+++ b/lib/topic_view.rb
@@ -342,7 +342,7 @@ class TopicView
 
     # Filters
     if @filter == 'summary'
-      @filtered_posts = @filtered_posts.summary
+      @filtered_posts = @filtered_posts.summary(@topic.id)
       @contains_gaps = true
     end