diff --git a/lib/elixir_script/module_systems/es.ex b/lib/elixir_script/module_systems/es.ex
index 54d2da9f..123656c7 100644
--- a/lib/elixir_script/module_systems/es.ex
+++ b/lib/elixir_script/module_systems/es.ex
@@ -12,6 +12,17 @@ defmodule ElixirScript.ModuleSystems.ES do
     imports ++ body ++ export
   end
 
+  def build_imports(js_imports) do
+    js_imports
+    |> Enum.map(fn
+      {_module, name, _path, import_path} -> import_module(name, import_path)
+    end)
+  end
+
+  def build_export(exports) do
+    if is_nil(exports), do: [], else: [export_module(exports)]
+  end
+
   defp import_module(import_name, from) do
     js_module_name = JS.identifier(import_name)
 
diff --git a/lib/elixir_script/passes/find_used_functions.ex b/lib/elixir_script/passes/find_used_functions.ex
index 94df537f..806d0c5e 100644
--- a/lib/elixir_script/passes/find_used_functions.ex
+++ b/lib/elixir_script/passes/find_used_functions.ex
@@ -9,18 +9,23 @@ defmodule ElixirScript.FindUsedFunctions do
   """
   @spec execute([atom], pid) :: nil
   def execute(entry_modules, pid) do
-    Enum.each(entry_modules, fn
+    entry_modules
+    |> List.wrap
+    |> Task.async_stream(fn
       module ->
         walk_module(module, pid)
     end)
+    |> Stream.run()
 
-    modules = ElixirScript.State.list_modules(pid)
-    Enum.each(modules, fn
+    pid
+    |> ElixirScript.State.list_modules
+    |> Task.async_stream(fn
       {module, info} ->
         if get_in(info, [:attributes, :protocol_impl]) do
           walk_module(module, pid)
         end
     end)
+    |> Stream.run()
   end
 
   defp walk_module(module, pid) do
diff --git a/lib/elixir_script/passes/find_used_modules.ex b/lib/elixir_script/passes/find_used_modules.ex
index 7c584775..2e9bc22f 100644
--- a/lib/elixir_script/passes/find_used_modules.ex
+++ b/lib/elixir_script/passes/find_used_modules.ex
@@ -8,11 +8,14 @@ defmodule ElixirScript.FindUsedModules do
   """
   @spec execute([atom], pid) :: nil
   def execute(modules, pid) do
-    Enum.each(List.wrap(modules), fn(module) ->
+    modules
+    |> List.wrap
+    |> Task.async_stream(fn(module) ->
       if ElixirScript.State.get_module(pid, module) == nil do
         do_execute(module, pid)
       end
     end)
+    |> Stream.run()
   end
 
   defp do_execute(module, pid) do
@@ -72,7 +75,6 @@ defmodule ElixirScript.FindUsedModules do
     }
 
     Enum.each(reachable_defs, &walk(&1, state))
-
   end
 
   defp walk_protocol(module, implementations, pid) do
@@ -128,7 +130,7 @@ defmodule ElixirScript.FindUsedModules do
   defp walk(form, state) when is_atom(form) and form not in [BitString, Function, PID, Port, Reference, Any, Elixir] do
     if ElixirScript.Translate.Module.is_elixir_module(form) and !ElixirScript.Translate.Module.is_js_module(form, state) do
       if ModuleState.get_module(state.pid, form) == nil do
-        execute(form, state.pid)
+        do_execute(form, state.pid)
       end
     end
   end
@@ -292,7 +294,7 @@ defmodule ElixirScript.FindUsedModules do
     cond do
       ElixirScript.Translate.Module.is_elixir_module(module) ->
         if ModuleState.get_module(state.pid, module) == nil do
-          execute(module, state.pid)
+          do_execute(module, state.pid)
         end
       true ->
         walk(module, state)
diff --git a/lib/elixir_script/passes/output.ex b/lib/elixir_script/passes/output.ex
index fc373936..83fec60a 100644
--- a/lib/elixir_script/passes/output.ex
+++ b/lib/elixir_script/passes/output.ex
@@ -35,10 +35,16 @@ defmodule ElixirScript.Output do
   defp bundle(modules, opts, js_modules) do
     modules
     |> ElixirScript.Output.JSModule.compile(opts, js_modules)
-    |> List.wrap
-    |> Builder.program
-    |> prepare_js_ast
-    |> Generator.generate
+    |> Task.async_stream(fn(js_part) ->
+      js_part
+      |> List.wrap
+      |> Builder.program
+      |> prepare_js_ast
+      |> Generator.generate
+    end)
+    |> Stream.map(fn {:ok, js_code} -> js_code end)
+    |> Enum.to_list
+    |> Enum.join("\n")
     |> concat
   end
 
diff --git a/lib/elixir_script/passes/output/js_module.ex b/lib/elixir_script/passes/output/js_module.ex
index af9f1b2c..3d093715 100644
--- a/lib/elixir_script/passes/output/js_module.ex
+++ b/lib/elixir_script/passes/output/js_module.ex
@@ -7,13 +7,10 @@ defmodule ElixirScript.Output.JSModule do
   def compile(body, opts, js_modules) do
     elixir = Helpers.declare("Elixir", J.object_expression([]))
 
-    ast = opts.module_formatter.build(
-      js_modules,
-      [elixir, create_atom_table(), start(), load()] ++ body,
-      J.identifier("Elixir")
-    )
+    imports = opts.module_formatter.build_imports(js_modules)
+    exports = opts.module_formatter.build_export(J.identifier("Elixir"))
 
-    ast
+    [elixir, create_atom_table(), start(), load(), imports, body, exports]
   end
 
   def start do
diff --git a/lib/elixir_script/passes/translate.ex b/lib/elixir_script/passes/translate.ex
index 11f89339..45f29204 100644
--- a/lib/elixir_script/passes/translate.ex
+++ b/lib/elixir_script/passes/translate.ex
@@ -8,9 +8,12 @@ defmodule ElixirScript.Translate do
   """
   @spec execute([atom], pid) :: nil
   def execute(modules, pid) do
-    Enum.each(modules, fn
+    modules
+    |> List.wrap()
+    |> Task.async_stream(fn
       {module, info} ->
         ElixirScript.Translate.Module.compile(module, info, pid)
     end)
+    |> Stream.run()
   end
 end
diff --git a/lib/elixir_script/passes/translate/identifier.ex b/lib/elixir_script/passes/translate/identifier.ex
index bd4664af..9d80f833 100644
--- a/lib/elixir_script/passes/translate/identifier.ex
+++ b/lib/elixir_script/passes/translate/identifier.ex
@@ -46,9 +46,15 @@ defmodule ElixirScript.Translate.Identifier do
   end
 
   defp filter_name(name) do
-    to_string(name)
-    |> String.replace("?", "__qmark__")
-    |> String.replace("!", "__emark__")
+    name = to_string(name)
+
+    if String.contains?(name, ["?", "!"]) do
+      name
+      |> String.replace("?", "__qmark__")
+      |> String.replace("!", "__emark__")
+    else
+      name
+    end
   end
 
   defp make_alias([x]) do
diff --git a/lib/elixir_script/state.ex b/lib/elixir_script/state.ex
index 03a74fba..78c0d418 100644
--- a/lib/elixir_script/state.ex
+++ b/lib/elixir_script/state.ex
@@ -25,7 +25,8 @@ defmodule ElixirScript.State do
   def put_module(pid, module, value) do
     Agent.update(pid, fn(state) ->
       value = Map.put(value, :used, [])
-      %{ state | modules: Keyword.put(state.modules, module, value) }
+      modules = Keyword.put(state.modules, module, value)
+      %{ state | modules: modules }
     end)
   end
 
@@ -41,7 +42,7 @@ defmodule ElixirScript.State do
       module_info = Keyword.get(state.modules, module)
 
       used = Map.get(module_info, :used, [])
-      used = used ++ [func]
+      used = [func | used]
 
       module_info = Map.put(module_info, :used, used)
       modules = Keyword.put(state.modules, module, module_info)
@@ -53,7 +54,7 @@ defmodule ElixirScript.State do
   def put_javascript_module(pid, module, name, path) do
     Agent.update(pid, fn(state) ->
       js_modules = Map.get(state, :js_modules, [])
-      js_modules = js_modules ++ [{module, name, path}]
+      js_modules = [{module, name, path} | js_modules]
       %{ state | js_modules: js_modules }
     end)
   end