Several performance improvements based on profiling.

app/lib/surface/Layer.coffee

@@ -35,12 +35,13 @@ module.exports = class Layer extends createjs.Container
     @transformStyle = options.transform ? Layer.TRANSFORM_CHILD
     @camera = options.camera
     console.error @toString(), "needs a camera." unless @camera
-    @updateLayerOrder = _.throttle @updateLayerOrder, 1  # don't call multiple times in one frame
+    @updateLayerOrder = _.throttle @updateLayerOrder, 1000 / 30  # Don't call multiple times in one frame; 30 FPS is probably good enough
     Backbone.Mediator.subscribe(channel, @[func], @) for channel, func of @subscriptions
 
   destroy: ->
     child.destroy?() for child in @children
     Backbone.Mediator.unsubscribe(channel, @[func], @) for channel, func of @subscriptions
+    delete @updateLayerOrder
 
   toString: -> "<Layer #{@layerPriority}: #{@name}>"
 
@@ -60,21 +61,30 @@ module.exports = class Layer extends createjs.Container
 
   updateLayerOrder: =>
     #console.log @, @toString(), "sorting children", _.clone @children if @name is 'Default'
-    @sortChildren (a, b) ->
-      alp = a.layerPriority ? 0
-      blp = b.layerPriority ? 0
-      return alp - blp if alp isnt blp
-      # TODO: remove this z stuff
-      az = if a.z then a.z else 1000
-      bz = if b.z then b.z else 1000
-      aThang = a.sprite?.thang
-      bThang = b.sprite?.thang
-      az -= 1 if aThang?.health < 0
-      bz -= 1 if bThang?.health < 0
-      if az == bz
-        return 0 unless aThang?.pos and bThang?.pos
-        return (bThang.pos.y - aThang.pos.y) or (bThang.pos.x - aThang.pos.x)
-      return az - bz
+    @sortChildren @layerOrderComparator
+
+  layerOrderComparator: (a, b) ->
+    # Optimize
+    alp = a.layerPriority or 0
+    blp = b.layerPriority or 0
+    return alp - blp if alp isnt blp
+    # TODO: remove this z stuff
+    az = a.z or 1000
+    bz = b.z or 1000
+    if aSprite = a.sprite
+      if aThang = aSprite.thang
+        aPos = aThang.pos
+        if aThang.health < 0
+          --az
+    if bSprite = b.sprite
+      if bThang = bSprite.thang
+        bPos = bThang.pos
+        if bThang.health < 0
+          --bz
+    if az is bz
+      return 0 unless aPos and bPos
+      return (bPos.y - aPos.y) or (bPos.x - aPos.x)
+    return az - bz
 
   onZoomUpdated: (e) ->
     return unless e.camera is @camera

app/lib/surface/SpriteBoss.coffee

@@ -34,17 +34,18 @@ module.exports = class SpriteBoss extends CocoClass
     @world = options.world
     @options.thangTypes ?= []
     @sprites = {}
+    @spriteArray = []  # Mirror @sprites, but faster for when we just need to iterate
     @selfWizardSprite = null
     @createLayers()
     @spriteSheetCache = {}
 
   destroy: ->
-    @removeSprite sprite for thangID, sprite of @sprites
+    @removeSprite sprite for sprite in @spriteArray
     @targetMark?.destroy()
     @selectionMark?.destroy()
     super()
 
-  toString: -> "<SpriteBoss: #{@sprites.length} sprites>"
+  toString: -> "<SpriteBoss: #{@spriteArray.length} sprites>"
 
   thangTypeFor: (type) ->
     _.find @options.thangTypes, (m) -> m.get('original') is type or m.get('name') is type
@@ -77,6 +78,7 @@ module.exports = class SpriteBoss extends CocoClass
     id ?= sprite.thang.id
     console.error "Sprite collision! Already have:", id if @sprites[id]
     @sprites[id] = sprite
+    @spriteArray.push sprite
     layer ?= @spriteLayers["Obstacle"] if sprite.thang?.spriteName.search(/(dungeon|indoor).wall/i) isnt -1
     layer ?= @layerForChild sprite.displayObject, sprite
     layer.addChild sprite.displayObject
@@ -117,7 +119,6 @@ module.exports = class SpriteBoss extends CocoClass
     else
       sprite.targetPos = if opponent.team is 'ogres' then {x:52, y: 28} else {x: 20, y:28}
 
-
   createWizardSprite: (options) ->
     sprite = new WizardSprite @thangTypeFor("Wizard"), @createSpriteOptions(options)
     @addSprite sprite, sprite.thang.id, @spriteLayers["Floating"]
@@ -138,7 +139,7 @@ module.exports = class SpriteBoss extends CocoClass
   onSetDebug: (e) ->
     return if e.debug is @debug
     @debug = e.debug
-    sprite.setDebug @debug for thangID, sprite of @sprites
+    sprite.setDebug @debug for sprite in @spriteArray
 
   onHighlightSprites: (e) ->
     highlightedIDs = e.thangIDs or []
@@ -159,15 +160,16 @@ module.exports = class SpriteBoss extends CocoClass
     sprite.displayObject.parent.removeChild sprite.displayObject
     thang = sprite.thang
     delete @sprites[sprite.thang.id]
+    @spriteArray.splice @spriteArray.indexOf(sprite), 1
     sprite.destroy()
     sprite.thang = thang  # Keep around so that we know which thang the destroyed thang was for
 
   updateSounds: ->
-    sprite.playSounds() for thangID, sprite of @sprites  # hmm; doesn't work for sprites which we didn't add yet in adjustSpriteExistence
+    sprite.playSounds() for sprite in @spriteArray  # hmm; doesn't work for sprites which we didn't add yet in adjustSpriteExistence
 
   update: (frameChanged) ->
     @adjustSpriteExistence() if frameChanged
-    sprite.update frameChanged for thangID, sprite of @sprites
+    sprite.update frameChanged for sprite in @spriteArray
     @updateSelection()
     @spriteLayers["Default"].updateLayerOrder()
     @cache()
@@ -197,7 +199,7 @@ module.exports = class SpriteBoss extends CocoClass
 
   cache: (update=false) ->
     return if @cached and not update
-    wallSprites = (sprite for thangID, sprite of @sprites when sprite.thangType?.get('name').search(/(dungeon|indoor).wall/i) isnt -1)
+    wallSprites = (sprite for sprite in @spriteArray when sprite.thangType?.get('name').search(/(dungeon|indoor).wall/i) isnt -1)
     walls = (sprite.thang for sprite in wallSprites)
     @world.calculateBounds()
     wallGrid = new Grid walls, @world.size()...
@@ -222,12 +224,12 @@ module.exports = class SpriteBoss extends CocoClass
   onCastSpells: -> @stop()
 
   play: ->
-    sprite.imageObject.play() for thangID, sprite of @sprites
+    sprite.imageObject.play() for sprite in @spriteArray
     @selectionMark?.play()
     @targetMark?.play()
 
   stop: ->
-    sprite.imageObject.stop() for thangID, sprite of @sprites
+    sprite.imageObject.stop() for sprite in @spriteArray
     @selectionMark?.stop()
     @targetMark?.stop()
 

app/lib/surface/Surface.coffee

@@ -221,8 +221,8 @@ module.exports = Surface = class Surface extends CocoClass
         @currentFrame = tempFrame
         frame = @world.getFrame(@getCurrentFrame())
         frame.restoreState()
-        for thangID, sprite of @spriteBoss.sprites
-          sprite.playSounds false, Math.max(0.05, Math.min(1, 1 / @scrubbingPlaybackSpeed))
+        volume = Math.max(0.05, Math.min(1, 1 / @scrubbingPlaybackSpeed))
+        sprite.playSounds false, volume for sprite in @spriteBoss.spriteArray
         tempFrame += if rising then 1 else -1
       @currentFrame = actualCurrentFrame
 

app/models/SuperModel.coffee

@@ -8,14 +8,14 @@ module.exports = class SuperModel extends Backbone.Model
 
     @models = {}
     @collections = {}
-    
+
   # Since the supermodel has undergone some changes into being a loader and a cache interface,
   # it's a bit wonky to use. The next couple functions are meant to cover the majority of
   # use cases across the site. If they are used, the view will automatically handle errors,
   # retries, progress, and filling the cache. Note that the resource it passes back will not
   # necessarily have the same model or collection that was passed in, if it was fetched from
   # the cache.
-    
+
   loadModel: (model, name, fetchOptions, value=1) ->
     cachedModel = @getModelByURL(model.getURL())
     if cachedModel
@@ -28,12 +28,12 @@ module.exports = class SuperModel extends Backbone.Model
         res = @addModelResource(cachedModel, name, fetchOptions, value)
         res.markLoading()
         return res
-    
+
     else
       @registerModel(model)
       console.debug 'Registering model', model.getURL()
       return @addModelResource(model, name, fetchOptions, value).load()
-      
+
   loadCollection: (collection, name, fetchOptions, value=1) ->
     url = collection.getURL()
     if cachedCollection = @collections[url]
@@ -46,7 +46,7 @@ module.exports = class SuperModel extends Backbone.Model
         res = @addModelResource(cachedCollection, name, fetchOptions, value)
         res.markLoading()
         return res
-        
+
     else
       @addCollection collection
       @listenToOnce collection, 'sync', (c) ->
@@ -56,7 +56,7 @@ module.exports = class SuperModel extends Backbone.Model
 
   # replace or overwrite
   shouldSaveBackups: (model) -> false
-    
+
   # Caching logic
 
   getModel: (ModelClass_or_url, id) ->
@@ -102,7 +102,7 @@ module.exports = class SuperModel extends Backbone.Model
       else
         @registerModel(model)
     collection
-    
+
   # Tracking resources being loaded for this supermodel
 
   finished: ->
@@ -148,7 +148,7 @@ module.exports = class SuperModel extends Backbone.Model
     @trigger('failed', source)
 
   updateProgress: =>
-    # Because this is _.defer'd, this might end up getting called after 
+    # Because this is _.defer'd, this might end up getting called after
     # a bunch of things load all at once.
     # So make sure we only emit events if @progress has changed.
     newProg = if @denom then @num / @denom else 1
@@ -161,8 +161,8 @@ module.exports = class SuperModel extends Backbone.Model
 
   getResource: (rid) ->
     return @resources[rid]
-    
-    
+
+
 
 class Resource extends Backbone.Model
   constructor: (name, value=1) ->
@@ -185,11 +185,11 @@ class Resource extends Backbone.Model
     @trigger('failed', {resource: @})
     @isLoaded = @isLoading = false
     @isFailed = true
-    
+
   markLoading: ->
     @isLoaded = @isFailed = false
     @isLoading = true
-    
+
   load: -> @
 
 

app/views/play/level/hud_view.coffee

@@ -306,10 +306,11 @@ module.exports = class HUDView extends View
     for actionName, action of @thang.actions
       @updateActionElement(actionName, @timespans[actionName], @thang.action is actionName)
     tableContainer = @$el.find('.table-container')
-    timelineWidth = tableContainer.find('tr:not(.secret) .action-timeline').width()
-    right = (1 - (@timeProgress ? 0)) * timelineWidth
     arrow = tableContainer.find('.progress-arrow')
-    arrow.css 'right', right - arrow.width() / 2
+    @timelineWidth ||= tableContainer.find('tr:not(.secret) .action-timeline').width()
+    @actionArrowWidth ||= arrow.width()
+    right = (1 - (@timeProgress ? 0)) * @timelineWidth
+    arrow.css 'right', right - @actionArrowWidth / 2
     tableContainer.find('.progress-line').css 'right', right
 
   buildActionTimespans: ->

app/views/play/level/playback_view.coffee

@@ -238,7 +238,7 @@ module.exports = class PlaybackView extends View
       @currentTime = e.frame / e.world.frameRate
       # Game will sometimes stop at 29.97, but with only one digit, this is unnecesary.
       # @currentTime = @totalTime if Math.abs(@totalTime - @currentTime) < 0.04
-      @updatePopupContent()
+      @updatePopupContent() if @timePopup?.shown
 
       @updateProgress(e.progress)
       @updatePlayButton(e.progress)

app/views/play/level/tome/thang_list_entry_view.coffee

@@ -156,9 +156,16 @@ module.exports = class ThangListEntryView extends View
     @$el.toggleClass('disabled', not enabled)
 
   onFrameChanged: (e) ->
+    # Optimize
     return unless currentThang = e.world.thangMap[@thang.id]
-    @$el.toggle Boolean(currentThang.exists)
-    @$el.toggleClass 'dead', currentThang.health <= 0 if currentThang.exists
+    exists = Boolean currentThang.exists
+    if @thangDidExist isnt exists
+      @$el.toggle exists
+      @thangDidExist = exists
+    dead = exists and currentThang.health <= 0
+    if @thangWasDead isnt dead
+      @$el.toggleClass 'dead', dead
+      @thangWasDead = dead
 
   destroy: ->
     @avatar?.destroy()