diff --git a/builds/4chan-X.user.js b/builds/4chan-X.user.js
index 2a4ef2216..4eccf46de 100644
--- a/builds/4chan-X.user.js
+++ b/builds/4chan-X.user.js
@@ -3145,7 +3145,7 @@
       for (threadID in _ref) {
         thread = _ref[threadID];
         if (thread.isHidden) {
-          if (_ref1 = thread.ID, __indexOf.call(Index.liveThreadIDs, _ref1) >= 0) {
+          if (_ref1 = thread.ID, __indexOf.call(Index.liveThreadData.keys, _ref1) >= 0) {
             hiddenCount++;
           }
         }
@@ -3265,34 +3265,32 @@
       return Index.buildIndex();
     },
     parseThreadList: function(pages) {
-      var data, i, live, page, thread;
+      var i, j, live, page, thread, threads;
       Index.threadsNumPerPage = pages[0].threads.length;
-      live = [];
+      live = new SimpleDict();
       i = 0;
       while (page = pages[i++]) {
-        live = live.concat(page.threads);
-      }
-      data = [];
-      i = 0;
-      while (thread = live[i++]) {
-        data.push(thread.no);
+        j = 0;
+        threads = page.threads;
+        while (thread = threads[j++]) {
+          live.push(thread.no, thread);
+        }
       }
       Index.liveThreadData = live;
-      Index.liveThreadIDs = data;
       return g.BOARD.threads.forEach(function(thread) {
         var _ref;
-        if (_ref = thread.ID, __indexOf.call(Index.liveThreadIDs, _ref) < 0) {
+        if (_ref = thread.ID, __indexOf.call(Index.liveThreadData.keys, _ref) < 0) {
           return thread.collect();
         }
       });
     },
     buildThreads: function() {
-      var err, errors, i, liveThreadData, posts, thread, threadData, threadRoot, threads;
+      var errors, posts, threads;
       threads = [];
       posts = [];
-      i = 0;
-      liveThreadData = Index.liveThreadData;
-      while (threadData = liveThreadData[i]) {
+      errors = null;
+      Index.liveThreadData.forEach(function(threadData) {
+        var err, thread, threadRoot;
         threadRoot = Build.thread(g.BOARD, threadData);
         if (thread = g.BOARD.threads[threadData.no]) {
           thread.setPage(Math.floor(i / Index.threadsNumPerPage));
@@ -3304,23 +3302,22 @@
           thread = new Thread(threadData.no, g.BOARD);
           threads.push(thread);
         }
-        i++;
         if (thread.ID in thread.posts) {
-          continue;
+          return;
         }
         try {
-          posts.push(new Post($('.opContainer', threadRoot), thread, g.BOARD));
+          return posts.push(new Post($('.opContainer', threadRoot), thread, g.BOARD));
         } catch (_error) {
           err = _error;
           if (!errors) {
             errors = [];
           }
-          errors.push({
+          return errors.push({
             message: "Parsing of Thread No." + thread + " failed. Thread will be skipped.",
             error: err
           });
         }
-      }
+      });
       if (errors) {
         Main.handleErrors(errors);
       }
@@ -3330,13 +3327,12 @@
       return $.event('IndexRefresh');
     },
     buildReplies: function(thread) {
-      var data, err, errors, i, lastReplies, node, nodes, post, posts, _i, _len;
+      var data, err, errors, lastReplies, node, nodes, post, posts, _i, _len;
       if (!Conf['Show Replies']) {
         return;
       }
       posts = [];
-      i = Index.liveThreadIDs.indexOf(thread.ID);
-      if (!(lastReplies = Index.liveThreadData[i].last_replies)) {
+      if (!(lastReplies = Index.liveThreadData[thread.ID].last_replies)) {
         return;
       }
       nodes = [];
@@ -3400,16 +3396,20 @@
       }
     },
     sort: function() {
-      var i, sortedThreadIDs, sortedThreads, thread, threadID;
+      var i, liveData, sortedThreadIDs, sortedThreads, thread, threadID;
       sortedThreads = [];
       sortedThreadIDs = [];
+      liveData = [];
+      Index.liveThreadData.forEach(function(data) {
+        return liveData.push(data);
+      });
       ({
         'bump': function() {
-          return sortedThreadIDs = Index.liveThreadIDs;
+          return sortedThreadIDs = Index.liveThreadData.keys;
         },
         'lastreply': function() {
-          var data, i, liveData;
-          liveData = __slice.call(Index.liveThreadData).sort(function(a, b) {
+          var data, i;
+          liveData.sort(function(a, b) {
             var _ref, _ref1;
             if ('last_replies' in a) {
               _ref = a.last_replies, a = _ref[_ref.length - 1];
@@ -3425,13 +3425,13 @@
           }
         },
         'birth': function() {
-          return sortedThreadIDs = __slice.call(Index.liveThreadIDs).sort(function(a, b) {
+          return sortedThreadIDs = __slice.call(Index.liveThreadData.keys).sort(function(a, b) {
             return b - a;
           });
         },
         'replycount': function() {
-          var data, i, liveData;
-          liveData = __slice.call(Index.liveThreadData).sort(function(a, b) {
+          var data, i;
+          liveData.sort(function(a, b) {
             return b.replies - a.replies;
           });
           i = 0;
@@ -3440,8 +3440,12 @@
           }
         },
         'filecount': function() {
-          var data, i, liveData;
-          liveData = __slice.call(Index.liveThreadData).sort(function(a, b) {
+          var data, i;
+          liveData = [];
+          Index.liveThreadData.forEach(function(data) {
+            return liveData.push(data);
+          });
+          liveData.sort(function(a, b) {
             return b.images - a.images;
           });
           i = 0;
@@ -3734,7 +3738,7 @@
       sticky = isSticky ? " <img src=" + staticPath + "sticky" + gifIcon + " title=Sticky class=stickyIcon>" : '';
       closed = isClosed ? " <img src=" + staticPath + "closed" + gifIcon + " title=Closed class=closedIcon>" : '';
       if (isOP && g.VIEW === 'index') {
-        pageNum = Math.floor(Index.liveThreadIDs.indexOf(postID) / Index.threadsNumPerPage);
+        pageNum = Math.floor(Index.liveThreadData.keys.indexOf(postID) / Index.threadsNumPerPage);
         pageIcon = " <span class=page-num title='This thread is on page " + pageNum + " in the original index.'>Page " + pageNum + "</span>";
         replyLink = " &nbsp; <span>[<a href='/" + boardID + "/res/" + threadID + "' class=replylink>Reply</a>]</span>";
       } else {
@@ -3800,10 +3804,10 @@
     catalogThread: function(thread) {
       var comment, data, fileCount, gifIcon, pageCount, postCount, pp, quotelink, root, spoilerRange, src, staticPath, subject, thumb, _i, _j, _len, _len1, _ref, _ref1;
       staticPath = Build.staticPath, gifIcon = Build.gifIcon;
-      data = Index.liveThreadData[Index.liveThreadIDs.indexOf(thread.ID)];
+      data = Index.liveThreadData[thread.ID];
       postCount = data.replies + 1;
       fileCount = data.images + !!data.ext;
-      pageCount = Math.floor(Index.liveThreadIDs.indexOf(thread.ID) / Index.threadsNumPerPage);
+      pageCount = Math.floor(Index.liveThreadData.keys.indexOf(thread.ID) / Index.threadsNumPerPage);
       subject = thread.OP.info.subject ? "<div class='subject'>" + thread.OP.info.subject + "</div>" : '';
       comment = thread.OP.nodes.comment.innerHTML.replace(/(<br>\s*){2,}/g, '<br>');
       root = $.el('div', {
diff --git a/builds/crx/script.js b/builds/crx/script.js
index bb77b4b2c..f36219a85 100644
--- a/builds/crx/script.js
+++ b/builds/crx/script.js
@@ -3204,7 +3204,7 @@
       for (threadID in _ref) {
         thread = _ref[threadID];
         if (thread.isHidden) {
-          if (_ref1 = thread.ID, __indexOf.call(Index.liveThreadIDs, _ref1) >= 0) {
+          if (_ref1 = thread.ID, __indexOf.call(Index.liveThreadData.keys, _ref1) >= 0) {
             hiddenCount++;
           }
         }
@@ -3324,34 +3324,32 @@
       return Index.buildIndex();
     },
     parseThreadList: function(pages) {
-      var data, i, live, page, thread;
+      var i, j, live, page, thread, threads;
       Index.threadsNumPerPage = pages[0].threads.length;
-      live = [];
+      live = new SimpleDict();
       i = 0;
       while (page = pages[i++]) {
-        live = live.concat(page.threads);
-      }
-      data = [];
-      i = 0;
-      while (thread = live[i++]) {
-        data.push(thread.no);
+        j = 0;
+        threads = page.threads;
+        while (thread = threads[j++]) {
+          live.push(thread.no, thread);
+        }
       }
       Index.liveThreadData = live;
-      Index.liveThreadIDs = data;
       return g.BOARD.threads.forEach(function(thread) {
         var _ref;
-        if (_ref = thread.ID, __indexOf.call(Index.liveThreadIDs, _ref) < 0) {
+        if (_ref = thread.ID, __indexOf.call(Index.liveThreadData.keys, _ref) < 0) {
           return thread.collect();
         }
       });
     },
     buildThreads: function() {
-      var err, errors, i, liveThreadData, posts, thread, threadData, threadRoot, threads;
+      var errors, posts, threads;
       threads = [];
       posts = [];
-      i = 0;
-      liveThreadData = Index.liveThreadData;
-      while (threadData = liveThreadData[i]) {
+      errors = null;
+      Index.liveThreadData.forEach(function(threadData) {
+        var err, thread, threadRoot;
         threadRoot = Build.thread(g.BOARD, threadData);
         if (thread = g.BOARD.threads[threadData.no]) {
           thread.setPage(Math.floor(i / Index.threadsNumPerPage));
@@ -3363,23 +3361,22 @@
           thread = new Thread(threadData.no, g.BOARD);
           threads.push(thread);
         }
-        i++;
         if (thread.ID in thread.posts) {
-          continue;
+          return;
         }
         try {
-          posts.push(new Post($('.opContainer', threadRoot), thread, g.BOARD));
+          return posts.push(new Post($('.opContainer', threadRoot), thread, g.BOARD));
         } catch (_error) {
           err = _error;
           if (!errors) {
             errors = [];
           }
-          errors.push({
+          return errors.push({
             message: "Parsing of Thread No." + thread + " failed. Thread will be skipped.",
             error: err
           });
         }
-      }
+      });
       if (errors) {
         Main.handleErrors(errors);
       }
@@ -3389,13 +3386,12 @@
       return $.event('IndexRefresh');
     },
     buildReplies: function(thread) {
-      var data, err, errors, i, lastReplies, node, nodes, post, posts, _i, _len;
+      var data, err, errors, lastReplies, node, nodes, post, posts, _i, _len;
       if (!Conf['Show Replies']) {
         return;
       }
       posts = [];
-      i = Index.liveThreadIDs.indexOf(thread.ID);
-      if (!(lastReplies = Index.liveThreadData[i].last_replies)) {
+      if (!(lastReplies = Index.liveThreadData[thread.ID].last_replies)) {
         return;
       }
       nodes = [];
@@ -3459,16 +3455,20 @@
       }
     },
     sort: function() {
-      var i, sortedThreadIDs, sortedThreads, thread, threadID;
+      var i, liveData, sortedThreadIDs, sortedThreads, thread, threadID;
       sortedThreads = [];
       sortedThreadIDs = [];
+      liveData = [];
+      Index.liveThreadData.forEach(function(data) {
+        return liveData.push(data);
+      });
       ({
         'bump': function() {
-          return sortedThreadIDs = Index.liveThreadIDs;
+          return sortedThreadIDs = Index.liveThreadData.keys;
         },
         'lastreply': function() {
-          var data, i, liveData;
-          liveData = __slice.call(Index.liveThreadData).sort(function(a, b) {
+          var data, i;
+          liveData.sort(function(a, b) {
             var _ref, _ref1;
             if ('last_replies' in a) {
               _ref = a.last_replies, a = _ref[_ref.length - 1];
@@ -3484,13 +3484,13 @@
           }
         },
         'birth': function() {
-          return sortedThreadIDs = __slice.call(Index.liveThreadIDs).sort(function(a, b) {
+          return sortedThreadIDs = __slice.call(Index.liveThreadData.keys).sort(function(a, b) {
             return b - a;
           });
         },
         'replycount': function() {
-          var data, i, liveData;
-          liveData = __slice.call(Index.liveThreadData).sort(function(a, b) {
+          var data, i;
+          liveData.sort(function(a, b) {
             return b.replies - a.replies;
           });
           i = 0;
@@ -3499,8 +3499,12 @@
           }
         },
         'filecount': function() {
-          var data, i, liveData;
-          liveData = __slice.call(Index.liveThreadData).sort(function(a, b) {
+          var data, i;
+          liveData = [];
+          Index.liveThreadData.forEach(function(data) {
+            return liveData.push(data);
+          });
+          liveData.sort(function(a, b) {
             return b.images - a.images;
           });
           i = 0;
@@ -3793,7 +3797,7 @@
       sticky = isSticky ? " <img src=" + staticPath + "sticky" + gifIcon + " title=Sticky class=stickyIcon>" : '';
       closed = isClosed ? " <img src=" + staticPath + "closed" + gifIcon + " title=Closed class=closedIcon>" : '';
       if (isOP && g.VIEW === 'index') {
-        pageNum = Math.floor(Index.liveThreadIDs.indexOf(postID) / Index.threadsNumPerPage);
+        pageNum = Math.floor(Index.liveThreadData.keys.indexOf(postID) / Index.threadsNumPerPage);
         pageIcon = " <span class=page-num title='This thread is on page " + pageNum + " in the original index.'>Page " + pageNum + "</span>";
         replyLink = " &nbsp; <span>[<a href='/" + boardID + "/res/" + threadID + "' class=replylink>Reply</a>]</span>";
       } else {
@@ -3859,10 +3863,10 @@
     catalogThread: function(thread) {
       var comment, data, fileCount, gifIcon, pageCount, postCount, pp, quotelink, root, spoilerRange, src, staticPath, subject, thumb, _i, _j, _len, _len1, _ref, _ref1;
       staticPath = Build.staticPath, gifIcon = Build.gifIcon;
-      data = Index.liveThreadData[Index.liveThreadIDs.indexOf(thread.ID)];
+      data = Index.liveThreadData[thread.ID];
       postCount = data.replies + 1;
       fileCount = data.images + !!data.ext;
-      pageCount = Math.floor(Index.liveThreadIDs.indexOf(thread.ID) / Index.threadsNumPerPage);
+      pageCount = Math.floor(Index.liveThreadData.keys.indexOf(thread.ID) / Index.threadsNumPerPage);
       subject = thread.OP.info.subject ? "<div class='subject'>" + thread.OP.info.subject + "</div>" : '';
       comment = thread.OP.nodes.comment.innerHTML.replace(/(<br>\s*){2,}/g, '<br>');
       root = $.el('div', {
diff --git a/src/General/Build.coffee b/src/General/Build.coffee
index b8e115d46..4896ea58a 100755
--- a/src/General/Build.coffee
+++ b/src/General/Build.coffee
@@ -181,7 +181,7 @@ Build =
       ''
 
     if isOP and g.VIEW is 'index'
-      pageNum   = Index.liveThreadIDs.indexOf(postID) // Index.threadsNumPerPage
+      pageNum   = Index.liveThreadData.keys.indexOf(postID) // Index.threadsNumPerPage
       pageIcon  = " <span class=page-num title='This thread is on page #{pageNum} in the original index.'>Page #{pageNum}</span>"
       replyLink = " &nbsp; <span>[<a href='/#{boardID}/res/#{threadID}' class=replylink>Reply</a>]</span>"
     else
@@ -237,11 +237,11 @@ Build =
 
   catalogThread: (thread) ->
     {staticPath, gifIcon} = Build
-    data = Index.liveThreadData[Index.liveThreadIDs.indexOf thread.ID]
+    data = Index.liveThreadData[thread.ID]
 
     postCount = data.replies + 1
     fileCount = data.images  + !!data.ext
-    pageCount = Index.liveThreadIDs.indexOf(thread.ID) // Index.threadsNumPerPage
+    pageCount = Index.liveThreadData.keys.indexOf(thread.ID) // Index.threadsNumPerPage
 
     subject = if thread.OP.info.subject
       "<div class='subject'>#{thread.OP.info.subject}</div>"
diff --git a/src/General/Index.coffee b/src/General/Index.coffee
index 4cdbf0a40..eced981d6 100644
--- a/src/General/Index.coffee
+++ b/src/General/Index.coffee
@@ -477,7 +477,7 @@ Index =
   updateHideLabel: ->
     hiddenCount = 0
     for threadID, thread of g.BOARD.threads when thread.isHidden
-      hiddenCount++ if thread.ID in Index.liveThreadIDs
+      hiddenCount++ if thread.ID in Index.liveThreadData.keys
     unless hiddenCount
       Index.hideLabel.hidden = true
       Index.cb.toggleHiddenThreads() if Index.showHiddenThreads
@@ -576,28 +576,25 @@ Index =
   parseThreadList: (pages) ->
     Index.threadsNumPerPage = pages[0].threads.length
 
-    live = []
+    live = new SimpleDict()
     i    = 0
     while page = pages[i++]
-      live = live.concat page.threads
+      j = 0
+      {threads} = page
+      while thread = threads[j++]
+        live.push thread.no, thread
 
-    data = []
-    i    = 0
-    while thread = live[i++]
-      data.push thread.no
-
-    Index.liveThreadData    = live
-    Index.liveThreadIDs     = data
+    Index.liveThreadData = live
 
     g.BOARD.threads.forEach (thread) ->
-      thread.collect() unless thread.ID in Index.liveThreadIDs
+      thread.collect() unless thread.ID in Index.liveThreadData.keys
 
   buildThreads: ->
     threads = []
     posts   = []
-    i = 0
-    {liveThreadData} = Index
-    while threadData = liveThreadData[i]
+    errors  = null
+
+    Index.liveThreadData.forEach (threadData) ->
       threadRoot = Build.thread g.BOARD, threadData
       if thread = g.BOARD.threads[threadData.no]
         thread.setPage i // Index.threadsNumPerPage
@@ -605,31 +602,34 @@ Index =
         thread.setCount 'file', threadData.images  + !!threadData.ext, threadData.imagelimit
         thread.setStatus 'Sticky', !!threadData.sticky
         thread.setStatus 'Closed', !!threadData.closed
+
       else
         thread = new Thread threadData.no, g.BOARD
         threads.push thread
-      i++
-      continue if thread.ID of thread.posts
+
+      return if thread.ID of thread.posts
+
       try
         posts.push new Post $('.opContainer', threadRoot), thread, g.BOARD
+
       catch err
         # Skip posts that we failed to parse.
         errors = [] unless errors
         errors.push
           message: "Parsing of Thread No.#{thread} failed. Thread will be skipped."
           error: err
-    Main.handleErrors errors if errors
 
+    Main.handleErrors  errors if errors
     Main.callbackNodes Thread, threads
     Main.callbackNodes Post,   posts
     Index.updateHideLabel()
+
     $.event 'IndexRefresh'
 
   buildReplies: (thread) ->
     return unless Conf['Show Replies']
     posts = []
-    i = Index.liveThreadIDs.indexOf thread.ID
-    return unless lastReplies = Index.liveThreadData[i].last_replies
+    return unless lastReplies = Index.liveThreadData[thread.ID].last_replies
     nodes = []
     for data in lastReplies
       if post = thread.posts[data.no]
@@ -676,11 +676,14 @@ Index =
     sortedThreads   = []
     sortedThreadIDs = []
 
+    liveData = []
+    Index.liveThreadData.forEach (data) -> liveData.push data
+
     {
       'bump': ->
-        sortedThreadIDs = Index.liveThreadIDs
+        sortedThreadIDs = Index.liveThreadData.keys
       'lastreply': ->
-        liveData = [Index.liveThreadData...].sort (a, b) ->
+        liveData.sort (a, b) ->
           [..., a] = a.last_replies if 'last_replies' of a
           [..., b] = b.last_replies if 'last_replies' of b
           b.no - a.no
@@ -689,15 +692,17 @@ Index =
           sortedThreadIDs.push data.no
         return
       'birth': ->
-        sortedThreadIDs = [Index.liveThreadIDs...].sort (a, b) -> b - a
+        sortedThreadIDs = [Index.liveThreadData.keys...].sort (a, b) -> b - a
       'replycount': ->
-        liveData = [Index.liveThreadData...].sort((a, b) -> b.replies - a.replies)
+        liveData.sort (a, b) -> b.replies - a.replies
         i = 0
         while data = liveData[i++]
           sortedThreadIDs.push data.no
         return
       'filecount': ->
-        liveData = [Index.liveThreadData...].sort((a, b) -> b.images - a.images)
+        liveData = []
+        Index.liveThreadData.forEach (data) -> liveData.push data
+        liveData.sort (a, b) -> b.images - a.images
         i = 0
         while data = liveData[i++]
           sortedThreadIDs.push data.no