Cache generated brush spans

app/assets/javascripts/player/brush.js.coffee

@@ -4,10 +4,13 @@ class AsciiIo.Brush
   @clearCache: ->
     @cache = {}
 
+  @hash: (brush) ->
+    "#{brush.fg}_#{brush.bg}_#{brush.bright}_#{brush.underline}"
+
   @create: (options) ->
     options ||= {}
 
-    key = "#{options.fg}_#{options.bg}_#{options.bright}_#{options.underline}"
+    key = @hash(options)
     brush = @cache[key]
 
     if not brush

app/assets/javascripts/player/terminal_view.js.coffee

@@ -5,6 +5,7 @@ class AsciiIo.TerminalView extends Backbone.View
   initialize: (options) ->
     @cols = options.cols
     @lines = options.lines
+    @cachedSpans = {}
 
     @createChildElements()
     @showCursor true
@@ -49,7 +50,7 @@ class AsciiIo.TerminalView extends Backbone.View
           if prevBrush
             html += '</span>'
 
-          html += @createSpan(brush, i is cursorX)
+          html += @spanFromBrush(brush, i is cursorX)
 
           prevBrush = brush
 
@@ -62,7 +63,11 @@ class AsciiIo.TerminalView extends Backbone.View
 
     @$el.find(".line:eq(" + n + ")").html html #.join("")
 
-  createSpan: (brush, hasCursor) ->
+  spanFromBrush: (brush, hasCursor) ->
+    key = "#{AsciiIo.Brush.hash(brush)}_#{hasCursor}"
+    span = @cachedSpans[key]
+
+    if not span
       span = ""
 
       if hasCursor or brush.fg isnt undefined or brush.bg isnt undefined or brush.bright or brush.underline
@@ -81,6 +86,8 @@ class AsciiIo.TerminalView extends Backbone.View
         span += " cursor visible" if hasCursor
         span += "\">"
 
+      @cachedSpans[key] = span
+
     span
 
   showCursor: (show) ->