diff --git a/_locales/de/messages.json b/_locales/de/messages.json
index d44dfc1..c9fa4c3 100644
--- a/_locales/de/messages.json
+++ b/_locales/de/messages.json
@@ -193,6 +193,15 @@
 		"description": ""
 	},
 	
+	"useCanvasCache_title": {
+		"message": "Zwischenspeicher für Canvas verwenden",
+		"description": ""
+	},
+	"useCanvasCache_description": {
+		"message": "Aktiviert den Canvas-Zwischenspeicher. Dies kann die Detektion des Addons verhindern und kann die Geschwindigkeit des Addons erhöhen, wenn kleine Canvas oft ausgelesen werden. Für große Canvas wird die Geschwindigkeit leider reduziert.",
+		"description": ""
+	},
+	
 	"disableNotifications": {
 		"message": "Benachrichtigungen deaktivieren",
 		"description": ""
diff --git a/_locales/en/messages.json b/_locales/en/messages.json
index 117b9b0..89ab240 100644
--- a/_locales/en/messages.json
+++ b/_locales/en/messages.json
@@ -193,6 +193,15 @@
 		"description": ""
 	},
 
+	"useCanvasCache_title": {
+		"message": "Use canvas cache",
+		"description": ""
+	},
+	"useCanvasCache_description": {
+		"message": "Enables the canvas cache. This can prevent detection and increases the performance when small canvas are read several times but decreases it for big canvas.",
+		"description": ""
+	},
+
 	"disableNotifications": {
 		"message": "disable notifications",
 		"description": ""
diff --git a/lib/defaultSettings.js b/lib/defaultSettings.js
index 4bc64c5..659d183 100644
--- a/lib/defaultSettings.js
+++ b/lib/defaultSettings.js
@@ -7,7 +7,8 @@ var settings = {
 	blockMode: "fakeReadout",
 	minFakeSize: 1,
 	maxFakeSize: 0,
-	rng: "constant",
+	rng: "nonPersistent",
+	useCanvasCache: true,
 	ignoreFrequentColors: 0,
 	persistentRndStorage: "",
 	storePersistentRnd: false,
diff --git a/lib/modifiedAPI.js b/lib/modifiedAPI.js
index 0be8e0f..ba5f3e3 100644
--- a/lib/modifiedAPI.js
+++ b/lib/modifiedAPI.js
@@ -54,8 +54,16 @@
 		};
 	}
 	
+	var canvasCache = Object.create(null);
 	function getFakeCanvas(window, original, prefs){
 		try {
+			if (prefs("useCanvasCache")){
+				var originalDataURL = original.toDataURL();
+				var cached = canvasCache[originalDataURL];
+				if (cached){
+					return cached;
+				}
+			}
 			// original may not be a canvas -> we must not leak an error
 			var context = getContext(window, original);
 			var {imageData, source} = getImageData(window, context);
@@ -86,6 +94,9 @@
 			var canvas = original.cloneNode(true);
 			context = window.HTMLCanvasElement.prototype.getContext.call(canvas, "2d");
 			context.putImageData(imageData, 0, 0);
+			if (prefs("useCanvasCache")){
+				canvasCache[originalDataURL] = canvas;
+			}
 			return canvas;
 		}
 		catch (e){
diff --git a/options/buildPrefInputs.js b/options/buildPrefInputs.js
index 9883436..e81a4f5 100644
--- a/options/buildPrefInputs.js
+++ b/options/buildPrefInputs.js
@@ -139,6 +139,15 @@ document.body.appendChild(table);
 			"blockMode": ["fakeReadout"]
 		}
 	},
+	{
+		"name": "useCanvasCache",
+		"title": "Use canvas cache",
+		"type": "bool",
+		"value": true,
+		"displayDependencies": {
+			"blockMode": ["fakeReadout"]
+		}
+	},
 	{
 		"name": "askOnlyOnce",
 		"title": "Ask only once",
diff --git a/releaseNotes.txt b/releaseNotes.txt
index 1f7a0cf..0b2ded9 100644
--- a/releaseNotes.txt
+++ b/releaseNotes.txt
@@ -16,6 +16,7 @@ Version 0.4.0:
 			* setting to enable the inspection of the content of the faked canvas
 			* new random number generator "constant"
 			* setting to not fake the most frequent colors in a canvas
+			* setting to enable canvas cache
 	
 	fixes:
 		- ask mode did not work for input types