Try the cache_digests gem for Tracks

cache_digests will be part of Rails 4

Gemfile

@@ -16,6 +16,8 @@ gem "aasm"
 gem "htmlentities"
 gem "swf_fu"
 gem "rails_autolink"
+gem "cache_digests" #, :git => 'git://github.com/rails/cache_digests.git'
+gem "rack-mini-profiler"
 
 # Gems used only for assets and not required
 # in production environments by default.
@@ -44,6 +46,7 @@ group :development do
   end
   gem "yard"
   gem "tolk"
+  gem "bullet"
 end
 
 group :test do

Gemfile.lock

@@ -41,6 +41,10 @@ GEM
     bcrypt-ruby (3.0.1)
     bluecloth (2.2.0)
     builder (3.0.0)
+    bullet (4.1.6)
+      uniform_notifier (~> 1.0.0)
+    cache_digests (0.1.0)
+      actionpack (>= 3.2)
     capybara (1.1.2)
       mime-types (>= 1.16)
       nokogiri (>= 1.3.3)
@@ -111,6 +115,8 @@ GEM
     rack (1.4.1)
     rack-cache (1.2)
       rack (>= 0.4)
+    rack-mini-profiler (0.1.10)
+      rack (>= 1.1.3)
     rack-ssl (1.3.2)
       rack
     rack-test (0.6.1)
@@ -178,6 +184,7 @@ GEM
     uglifier (1.2.7)
       execjs (>= 0.3.0)
       multi_json (~> 1.3)
+    uniform_notifier (1.0.2)
     will_paginate (3.0.3)
     xpath (0.1.4)
       nokogiri (~> 1.3)
@@ -193,6 +200,8 @@ DEPENDENCIES
   acts_as_list
   aruba
   bcrypt-ruby
+  bullet
+  cache_digests
   capybara
   coffee-rails
   cucumber-rails
@@ -203,6 +212,7 @@ DEPENDENCIES
   jquery-rails
   mongrel (>= 1.2.0.pre2)
   mysql2
+  rack-mini-profiler
   rails
   rails_autolink
   sanitize

app/controllers/contexts_controller.rb

@@ -50,23 +50,20 @@ class ContextsController < ApplicationController
       @pending = @context.todos.pending.includes(Todo::DEFAULT_INCLUDES)
         
       @projects = current_user.projects
+      @contexts = current_user.contexts
 
       @count = @not_done_todos.count + @deferred.count + @pending.count
-    end
-    
-    @contexts = current_user.contexts(true)
-    if @context.nil?
-      respond_to do |format|
-        format.html { render :text => 'Context not found', :status => 404 }
-        format.xml  { render :xml => '<error>Context not found</error>', :status => 404 }
-      end
-    else
       @page_title = "TRACKS::Context: #{@context.name}"
       respond_to do |format|
         format.html
         format.m    &render_context_mobile
         format.xml  { render :xml => @context.to_xml( :except => :user_id ) }
       end
+    else
+      respond_to do |format|
+        format.html { render :text => 'Context not found', :status => 404 }
+        format.xml  { render :xml => '<error>Context not found</error>', :status => 404 }
+      end
     end
   end
   

app/models/todo.rb

@@ -4,8 +4,8 @@ class Todo < ActiveRecord::Base
   after_save :save_predecessors
 
   # associations
-  belongs_to :context
-  belongs_to :project
+  belongs_to :context, :touch => true
+  belongs_to :project, :touch => true
   belongs_to :user
   belongs_to :recurring_todo
 

app/views/contexts/_context.html.erb

@@ -1,4 +1,7 @@
-<% @not_done = @not_done_todos.select {|t| t.context_id == context.id } -%>
+<%
+@not_done = @not_done_todos.select {|t| t.context_id == context.id }
+cache context do
+%>
   <div id="c<%= context.id %>" class="container context" style="display:<%= (collapsible && @not_done.empty?) ? "none" : "block" %>">
     <h2>
       <% if collapsible -%>
@@ -18,3 +21,4 @@
       <%= render :partial => "todos/todo", :collection => @not_done, :locals => { :parent_container_type => "context" } %>
     </div>
   </div>
+<% end %>

app/views/projects/_project.html.erb

@@ -1,3 +1,4 @@
+<% cache project do %>
   <div class="container">
     <h2 id="project_name_container">
       <% if collapsible -%>
@@ -19,3 +20,4 @@
       <%= render :partial => "todos/todo", :collection => @not_done, :locals => { :parent_container_type => "project" } %>
     </div>
   </div>
+<% end %>

app/views/todos/_successor.html.erb

@@ -6,6 +6,8 @@ parameters = "_source_view=#{@source_view}"
 parameters += "&_tag_name=#{@tag_name}" if @source_view == 'tag'
 @z_index_counter = @z_index_counter - 1  # for IE z-index bug
 @rec_depth ||= 0
+
+cache successor do
 %>
   <div id="<%= dom_id(successor, 'successor') %>" class="item-container">
     <div id="<%= dom_id(successor, 'successor_line') %>">
@@ -33,3 +35,4 @@ parameters += "&_tag_name=#{@tag_name}" if @source_view == 'tag'
       </div>
     </div>
   </div>
+<% end %>

app/views/todos/_todo.html.erb

@@ -6,6 +6,8 @@ parameters = "_source_view=#{@source_view}"
 parameters += "&_tag_name=#{@tag_name}" if @source_view == 'tag'
 @z_index_counter = @z_index_counter - 1  # for IE z-index bug
 @rec_depth=0 # to prevent stack overflow on large dependency trees, see _successor.html.erb
+
+cache todo do
 %>
   <div id="<%= dom_id(todo) %>" class="item-container">
     <div id="<%= dom_id(todo, 'line') %>" class="item-show">
@@ -43,3 +45,4 @@ parameters += "&_tag_name=#{@tag_name}" if @source_view == 'tag'
       <div class="placeholder"> </div>
     </div>
   </div>
+<% end %>

config/initializers/bullet.rb

@@ -0,0 +1,7 @@
+# config for bullet gem
+
+if defined? Bullet
+  Bullet.enable = false
+  Bullet.alert = false
+  Bullet.bullet_logger = true
+end