Elm-lang app that needs speed boost

app.elm

import Html exposing (..)
import Debug exposing (..)
import Array exposing (Array, repeat, set, get, toList, initialize)
import Html.Attributes exposing (..)
import Html.Events exposing (on, onClick, targetChecked)
import Signal exposing (Address)
import StartApp.Simple as StartApp


main =
  StartApp.start { model = initialModel, view = view, update = update }

-- MODEL

type alias Model = Array Bool

w = 400
h = 400

initialModel = repeat (w * h) False


-- UPDATE

type Action
  = Hi Int


update action model =
  case action of
    Hi i ->
      let newval = if (get i model) == Just True then False else True
      in
      set i newval model

-- VIEW
view address model =
   table [ style [("border-collapse", "collapse")] ] (toList (initialize h (\row ->
      tr [] (toList (initialize w (\col ->
        let i = w*row+col
            bg = if (get i model)== Just True then "blue" else "white"
        in
        td [ onClick address (Hi i), style [("background", bg)] ] [ text "*" ]
      )))
    )))