diff --git a/src/Filtering/Filter.coffee b/src/Filtering/Filter.coffee
index a98ac59a9..281bed112 100644
--- a/src/Filtering/Filter.coffee
+++ b/src/Filtering/Filter.coffee
@@ -98,6 +98,7 @@ Filter =
   parseBoards: (boardsRaw) ->
     return false unless boardsRaw
     boardsRaw = boardsRaw.toLowerCase()
+    return boards if (boards = Filter.parseBoardsMemo[boardsRaw])
     boards = {}
     siteFilter = ''
     for boardID in boardsRaw.split(',')
@@ -110,8 +111,11 @@ Filter =
             boards["#{siteID}/#{boardID2}"] = true
         else
           boards["#{siteID}/#{boardID}"] = true
+    Filter.parseBoardsMemo[boardsRaw] = boards
     boards
 
+  parseBoardsMemo: {}
+
   test: (post, hideable=true) ->
     return post.filterResults if post.filterResults
     hide = false