diff --git a/src/js/Constants.js b/src/js/Constants.js
index ad93d15d..2f112e3e 100644
--- a/src/js/Constants.js
+++ b/src/js/Constants.js
@@ -11,6 +11,8 @@ var Constants = {
   MAX_HEIGHT : 1024,
   MAX_WIDTH : 1024,
 
+  MAX_CURRENT_COLORS_DISPLAYED : 100,
+
   MINIMUM_ZOOM : 1,
 
   PREVIEW_FILM_SIZE : 96,
diff --git a/src/js/controller/PalettesListController.js b/src/js/controller/PalettesListController.js
index 29ea5821..0901d3df 100644
--- a/src/js/controller/PalettesListController.js
+++ b/src/js/controller/PalettesListController.js
@@ -10,7 +10,6 @@
   // I apologize to my future self for this one.
   var NO_SCROLL_MAX_COLORS = 20;
 
-  var MAX_COLORS = 100;
 
   ns.PalettesListController = function (paletteController, usedColorService) {
     this.usedColorService = usedColorService;
@@ -80,8 +79,8 @@
       }
     }
 
-    if (colors.length > MAX_COLORS) {
-      colors = colors.slice(0, MAX_COLORS);
+    if (colors.length > Constants.MAX_CURRENT_COLORS_DISPLAYED) {
+      colors = colors.slice(0, Constants.MAX_CURRENT_COLORS_DISPLAYED);
     }
 
     return colors;
diff --git a/src/js/controller/PreviewFilmController.js b/src/js/controller/PreviewFilmController.js
index bbca4eda..d61a80c6 100644
--- a/src/js/controller/PreviewFilmController.js
+++ b/src/js/controller/PreviewFilmController.js
@@ -15,6 +15,10 @@
     this.refreshZoom_();
 
     this.redrawFlag = true;
+
+    this.cachedFrameProcessor = new pskl.model.frame.CachedFrameProcessor();
+    this.cachedFrameProcessor.setFrameProcessor(this.frameToPreviewCanvas_.bind(this));
+    this.cachedFrameProcessor.setOutputCloner(this.clonePreviewCanvas_.bind(this));
   };
 
   ns.PreviewFilmController.prototype.init = function() {
@@ -39,7 +43,6 @@
 
   ns.PreviewFilmController.prototype.render = function () {
     if (this.redrawFlag) {
-      // TODO(vincz): Full redraw on any drawing modification, optimize.
       this.createPreviews_();
       this.redrawFlag = false;
     }
@@ -175,11 +178,8 @@
     cloneFrameButton.className = "tile-overlay duplicate-frame-action";
     previewTileRoot.appendChild(cloneFrameButton);
 
-    var canvasRenderer = new pskl.rendering.CanvasRenderer(currentFrame, this.zoom);
-    canvasRenderer.drawTransparentAs(Constants.TRANSPARENT_COLOR);
-    var canvas = canvasRenderer.render();
-    canvas.classList.add('tile-view', 'canvas');
-    canvasContainer.appendChild(canvas);
+
+    canvasContainer.appendChild(this.getCanvasForFrame(currentFrame));
     previewTileRoot.appendChild(canvasContainer);
 
     if(tileNumber > 0 || this.piskelController.getFrameCount() > 1) {
@@ -206,6 +206,25 @@
     return previewTileRoot;
   };
 
+  ns.PreviewFilmController.prototype.getCanvasForFrame = function (frame) {
+    var canvas = this.cachedFrameProcessor.get(frame, this.zoom);
+    return canvas;
+  };
+
+  ns.PreviewFilmController.prototype.frameToPreviewCanvas_ = function (frame) {
+    var canvasRenderer = new pskl.rendering.CanvasRenderer(frame, this.zoom);
+    canvasRenderer.drawTransparentAs(Constants.TRANSPARENT_COLOR);
+    var canvas = canvasRenderer.render();
+    canvas.classList.add('tile-view', 'canvas');
+    return canvas;
+  };
+
+  ns.PreviewFilmController.prototype.clonePreviewCanvas_ = function (canvas) {
+    var clone = pskl.CanvasUtils.clone(canvas);
+    clone.classList.add('tile-view', 'canvas');
+    return clone;
+  };
+
   /**
    * Calculate the preview zoom depending on the piskel size
    */
diff --git a/src/js/controller/piskel/PiskelController.js b/src/js/controller/piskel/PiskelController.js
index a66a5875..b337866e 100644
--- a/src/js/controller/piskel/PiskelController.js
+++ b/src/js/controller/piskel/PiskelController.js
@@ -77,10 +77,16 @@
   };
 
   ns.PiskelController.prototype.getFrameAt = function (index) {
+    var hash = [];
     var frames = this.getLayers().map(function (l) {
-      return l.getFrameAt(index);
+      var frame = l.getFrameAt(index);
+      hash.push(frame.getHash());
+      return frame;
     });
-    return pskl.utils.FrameUtils.merge(frames);
+    var mergedFrame = pskl.utils.FrameUtils.merge(frames);
+    mergedFrame.id = hash.join('-');
+    mergedFrame.version = 0;
+    return mergedFrame;
   };
 
   ns.PiskelController.prototype.hasFrameAt = function (index) {
diff --git a/src/js/controller/settings/SaveController.js b/src/js/controller/settings/SaveController.js
index b79a49f2..f3dd63ba 100644
--- a/src/js/controller/settings/SaveController.js
+++ b/src/js/controller/settings/SaveController.js
@@ -62,12 +62,26 @@
     evt.preventDefault();
     evt.stopPropagation();
 
-    this.beforeSaving_();
-    pskl.app.storageService.store({
-      success : this.onSaveSuccess_.bind(this),
-      error : this.onSaveError_.bind(this),
-      after : this.afterSaving_.bind(this)
-    });
+    var name = this.getName();
+
+    if (!name) {
+      name = window.prompt('Please specify a name', 'New piskel');
+    }
+
+    if (name) {
+      var description = this.getDescription();
+      var isPublic = !!this.isPublicCheckbox.prop('checked');
+
+      var descriptor = new pskl.model.piskel.Descriptor(name, description, isPublic);
+      this.piskelController.getPiskel().setDescriptor(descriptor);
+
+      this.beforeSaving_();
+      pskl.app.storageService.store({
+        success : this.onSaveSuccess_.bind(this),
+        error : this.onSaveError_.bind(this),
+        after : this.afterSaving_.bind(this)
+      });
+    }
   };
 
   ns.SaveController.prototype.onSaveLocalClick_ = function (evt) {
diff --git a/src/js/drawingtools/Lighten.js b/src/js/drawingtools/Lighten.js
index 78a3a7ed..fc897a2e 100644
--- a/src/js/drawingtools/Lighten.js
+++ b/src/js/drawingtools/Lighten.js
@@ -27,7 +27,9 @@
    * @override
    */
   ns.Lighten.prototype.applyToolAt = function(col, row, color, frame, overlay, event, mouseButton) {
-    var pixelColor = frame.getPixel(col, row);
+    var overlayColor = overlay.getPixel(col, row);
+    var frameColor = frame.getPixel(col, row);
+    var pixelColor = overlayColor === Constants.TRANSPARENT_COLOR ? frameColor : overlayColor;
 
     var isDarken = event.ctrlKey || event.cmdKey;
     var isSinglePass = event.shiftKey;
@@ -55,7 +57,11 @@
   };
 
   ns.Lighten.prototype.releaseToolAt = function(col, row, color, frame, overlay, event) {
+    // apply on real frame
+    this.setPixelsToFrame_(frame, this.pixels);
+
     this.resetUsedPixels_();
+
     $.publish(Events.PISKEL_SAVE_STATE, {
       type : pskl.service.HistoryService.SNAPSHOT
     });
diff --git a/src/js/drawingtools/SimplePen.js b/src/js/drawingtools/SimplePen.js
index dd9ab9ce..f36ec667 100644
--- a/src/js/drawingtools/SimplePen.js
+++ b/src/js/drawingtools/SimplePen.js
@@ -22,12 +22,17 @@
    * @override
    */
   ns.SimplePen.prototype.applyToolAt = function(col, row, color, frame, overlay, event) {
-    frame.setPixel(col, row, color);
+    overlay.setPixel(col, row, color);
+
+    if (color === Constants.TRANSPARENT_COLOR) {
+      frame.setPixel(col, row, color);
+    }
     this.previousCol = col;
     this.previousRow = row;
     this.pixels.push({
       col : col,
-      row : row
+      row : row,
+      color : color
     });
   };
 
@@ -55,17 +60,26 @@
 
 
   ns.SimplePen.prototype.releaseToolAt = function(col, row, color, frame, overlay, event) {
+    // apply on real frame
+    this.setPixelsToFrame_(frame, this.pixels);
+
+    // save state
     this.raiseSaveStateEvent({
       pixels : this.pixels.slice(0),
       color : color
     });
+
+    // reset
     this.pixels = [];
   };
 
   ns.SimplePen.prototype.replay = function (frame, replayData) {
-    var pixels = replayData.pixels;
+    this.setPixelsToFrame_(frame, replayData.pixels, replayData.color);
+  };
+
+  ns.SimplePen.prototype.setPixelsToFrame_ = function (frame, pixels, color) {
     pixels.forEach(function (pixel) {
-      frame.setPixel(pixel.col, pixel.row, replayData.color);
+      frame.setPixel(pixel.col, pixel.row, pixel.color);
     });
   };
 })();
diff --git a/src/js/model/frame/CachedFrameProcessor.js b/src/js/model/frame/CachedFrameProcessor.js
new file mode 100644
index 00000000..3c0c07aa
--- /dev/null
+++ b/src/js/model/frame/CachedFrameProcessor.js
@@ -0,0 +1,79 @@
+(function () {
+  var ns = $.namespace('pskl.model.frame');
+
+
+  var DEFAULT_CLEAR_INTERVAL = 10 * 60 *1000;
+
+  var DEFAULT_FRAME_PROCESSOR = function (frame) {
+    return pskl.utils.FrameUtils.toImage(frame);
+  };
+
+  var DEFAULT_OUTPUT_CLONER = function (o) {return o;};
+
+  var DEFAULT_NAMESPACE = '__cache_default__';
+
+  ns.CachedFrameProcessor = function (cacheResetInterval) {
+    this.cache_ = {};
+    this.cacheResetInterval = cacheResetInterval || DEFAULT_CLEAR_INTERVAL;
+    this.frameProcessor = DEFAULT_FRAME_PROCESSOR;
+    this.outputCloner = DEFAULT_OUTPUT_CLONER;
+
+    window.setInterval(this.clear.bind(this), this.cacheResetInterval);
+  };
+
+  ns.CachedFrameProcessor.prototype.clear = function () {
+    this.cache_ = {};
+  };
+
+  /**
+   * Set the processor function that will be called when there is a cache miss
+   * Function with 1 argument : pskl.model.Frame
+   * @param {Function} frameProcessor
+   */
+  ns.CachedFrameProcessor.prototype.setFrameProcessor = function (frameProcessor) {
+    this.frameProcessor = frameProcessor;
+  };
+
+  /**
+   * Set the cloner that will be called when there is a miss on the 1st level cache
+   * but a hit on the 2nd level cache.
+   * Function with 2 arguments : cached value, frame
+   * @param {Function} outputCloner
+   */
+  ns.CachedFrameProcessor.prototype.setOutputCloner = function (outputCloner) {
+    this.outputCloner = outputCloner;
+  };
+
+  /**
+   * Retrieve the processed frame from the cache, in the (optional) namespace
+   * If the first level cache is empty, attempt to clone it from 2nd level cache. If second level cache is empty process the frame.
+   * @param  {pskl.model.Frame} frame
+   * @param  {String} namespace
+   * @return {Object} the processed frame
+   */
+  ns.CachedFrameProcessor.prototype.get = function (frame, namespace) {
+    var processedFrame = null;
+    namespace = namespace || DEFAULT_NAMESPACE;
+
+    if (!this.cache_[namespace]) {
+      this.cache_[namespace] = {};
+    }
+
+    var cache = this.cache_[namespace];
+
+    var cacheKey = frame.getHash();
+    if (this.cache_[cacheKey]) {
+      processedFrame = this.cache_[cacheKey];
+    } else {
+      var frameAsString = JSON.stringify(frame.getPixels());
+      if (this.cache_[frameAsString]) {
+        processedFrame = this.outputCloner(this.cache_[frameAsString], frame);
+      } else {
+        processedFrame = this.frameProcessor(frame);
+        this.cache_[frameAsString] = processedFrame;
+      }
+      this.cache_[cacheKey] = processedFrame;
+    }
+    return processedFrame;
+  };
+})();
\ No newline at end of file
diff --git a/src/js/rendering/frame/TiledFrameRenderer.js b/src/js/rendering/frame/TiledFrameRenderer.js
index 4b41bb1d..9eabb8dc 100644
--- a/src/js/rendering/frame/TiledFrameRenderer.js
+++ b/src/js/rendering/frame/TiledFrameRenderer.js
@@ -8,11 +8,19 @@
     this.displayContainer = document.createElement('div');
     this.displayContainer.classList.add('tiled-frame-container');
     container.get(0).appendChild(this.displayContainer);
+
+    this.cachedFrameProcessor = new pskl.model.frame.CachedFrameProcessor();
+    this.cachedFrameProcessor.setFrameProcessor(this.frameToDataUrl_.bind(this));
+  };
+
+  ns.TiledFrameRenderer.prototype.frameToDataUrl_ = function (frame) {
+    var canvas = new pskl.utils.FrameUtils.toImage(frame, this.zoom);
+    return canvas.toDataURL('image/png');
   };
 
   ns.TiledFrameRenderer.prototype.render = function (frame) {
-    var canvas = new pskl.utils.FrameUtils.toImage(frame, this.zoom);
-    this.displayContainer.style.backgroundImage = 'url(' + canvas.toDataURL('image/png') + ')';
+    var imageSrc = this.cachedFrameProcessor.get(frame, this.zoom);
+    this.displayContainer.style.backgroundImage = 'url(' + imageSrc + ')';
   };
 
   ns.TiledFrameRenderer.prototype.show = function () {
diff --git a/src/js/service/BackupService.js b/src/js/service/BackupService.js
index 8b884fbc..59e9a23a 100644
--- a/src/js/service/BackupService.js
+++ b/src/js/service/BackupService.js
@@ -1,6 +1,6 @@
 (function () {
   var ns = $.namespace('pskl.service');
-  var BACKUP_INTERVAL = 1000 * 30;
+  var BACKUP_INTERVAL = 1000 * 60;
 
   ns.BackupService = function (piskelController) {
     this.piskelController = piskelController;
diff --git a/src/js/service/CurrentColorsService.js b/src/js/service/CurrentColorsService.js
index e8f282cf..4aed52e7 100644
--- a/src/js/service/CurrentColorsService.js
+++ b/src/js/service/CurrentColorsService.js
@@ -4,6 +4,9 @@
   ns.CurrentColorsService = function (piskelController) {
     this.piskelController = piskelController;
     this.currentColors = [];
+    this.cachedFrameProcessor = new pskl.model.frame.CachedFrameProcessor();
+    this.cachedFrameProcessor.setFrameProcessor(this.frameToColors_.bind(this));
+
     this.framesColorsCache_ = {};
   };
 
@@ -16,33 +19,35 @@
     return this.currentColors;
   };
 
+  ns.CurrentColorsService.prototype.frameToColors_ = function (frame) {
+    var frameColors = {};
+    frame.forEachPixel(function (color, x, y) {
+      frameColors[color] = (frameColors[color] || 0) + 1;
+    });
+    return frameColors;
+  };
+
+
   ns.CurrentColorsService.prototype.onPiskelUpdated_ = function (evt) {
     var layers = this.piskelController.getLayers();
     var frames = layers.map(function (l) {return l.getFrames();}).reduce(function (p, n) {return p.concat(n);});
     var colors = {};
     frames.forEach(function (f) {
-      var frameHash = f.getHash();
-      if (!this.framesColorsCache_[frameHash]) {
-        var frameColors = {};
-        f.forEachPixel(function (color, x, y) {
-          frameColors[color] = true;
-        });
-        this.framesColorsCache_[frameHash] = frameColors;
-      }
-      Object.keys(this.framesColorsCache_[frameHash]).forEach(function (color) {
-        colors[color] = true;
+      var frameColors = this.cachedFrameProcessor.get(f);
+      Object.keys(frameColors).slice(0, Constants.MAX_CURRENT_COLORS_DISPLAYED).forEach(function (color) {
+        colors[color] = (colors[color] || 0) + frameColors[color];
       });
     }.bind(this));
+
+    // Remove transparent color from used colors
     delete colors[Constants.TRANSPARENT_COLOR];
-    this.currentColors = Object.keys(colors);
+
+    // limit the array to the max colors to display
+    this.currentColors = Object.keys(colors).slice(0, Constants.MAX_CURRENT_COLORS_DISPLAYED);
+
+    // sort by most frequent color
     this.currentColors = this.currentColors.sort(function (c1, c2) {
-      if (c1 < c2) {
-        return -1;
-      } else if (c1 > c2) {
-        return 1;
-      } else {
-        return 0;
-      }
+      return colors[c2] - colors[c1];
     });
 
     // TODO : only fire if there was a change
diff --git a/src/js/utils/CanvasUtils.js b/src/js/utils/CanvasUtils.js
index a6eca20e..8ef9d161 100644
--- a/src/js/utils/CanvasUtils.js
+++ b/src/js/utils/CanvasUtils.js
@@ -48,6 +48,16 @@
       }
     },
 
+    clone : function (canvas) {
+      var clone = pskl.CanvasUtils.createCanvas(canvas.width, canvas.height);
+
+      //apply the old canvas to the new one
+      clone.getContext('2d').drawImage(canvas, 0, 0);
+
+      //return the new canvas
+      return clone;
+    },
+
     getImageDataFromCanvas : function (canvas) {
       var sourceContext = canvas.getContext('2d');
       return sourceContext.getImageData(0, 0, canvas.width, canvas.height).data;
diff --git a/src/piskel-script-list.js b/src/piskel-script-list.js
index bde5fe67..cdad6616 100644
--- a/src/piskel-script-list.js
+++ b/src/piskel-script-list.js
@@ -48,6 +48,7 @@
   "js/model/Frame.js",
   "js/model/Layer.js",
   "js/model/piskel/Descriptor.js",
+  "js/model/frame/CachedFrameProcessor.js",
   "js/model/Piskel.js",
 
   // Selection