diff --git a/package.json b/package.json
index 699941f..1339d5e 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "graphfx",
-  "version": "0.0.3",
+  "version": "0.0.4",
   "description": "Graph image processing pipeline",
   "main": "src/index.js",
   "scripts": {
diff --git a/src/graph.js b/src/graph.js
index 724cfb0..6dae141 100644
--- a/src/graph.js
+++ b/src/graph.js
@@ -38,6 +38,12 @@ export default class Graph {
         return results;
     }
 
+    destroy() {
+        for(let {node} of this.nodes) {
+            node.destroy();
+        }
+    }
+
 }
 
 
diff --git a/src/nodes/Canvas2d/Canvas2d.js b/src/nodes/Canvas2d/Canvas2d.js
index c357476..7d5b770 100644
--- a/src/nodes/Canvas2d/Canvas2d.js
+++ b/src/nodes/Canvas2d/Canvas2d.js
@@ -25,6 +25,11 @@ export default class Canvas2d extends Node {
         this.__canvas = document.createElement('canvas');
     }
 
+    destroy() {
+        this.__canvas = null;
+        super.destroy();
+    }
+
     async _update() {
         const values = {};
         for (let name of Object.keys(this.in.variables)) {
@@ -37,8 +42,12 @@ export default class Canvas2d extends Node {
         const result = await this.render(values, this.__canvas, ctx);
         if (result instanceof ImageBitmap) {
             this.__out.image.value = result;
-            this.out.width.value = this.out.image.value.width;
-            this.out.height.value = this.out.image.value.height;
+            if (this.out.width.value !== this.out.image.value.width) {
+                this.out.width.value = this.out.image.value.width;
+            }
+            if (this.out.height.value !== this.out.image.value.height) {
+                this.out.height.value = this.out.image.value.height;
+            }
         }
     }
 
diff --git a/src/nodes/Canvas2d/Text.js b/src/nodes/Canvas2d/Text.js
index d91cdca..3e3766a 100644
--- a/src/nodes/Canvas2d/Text.js
+++ b/src/nodes/Canvas2d/Text.js
@@ -65,7 +65,6 @@ export default class Resize extends Canvas2d {
         ctx.textAlign = textAlign;
         const x = textAlign === 'center' ? canvas.width /2 :
             textAlign === 'left' ? 0 : canvas.width;
-        console.log(text.split('\\n'));
         text.split('\\n').forEach((line, index) => {
             ctx.fillText(line, x, fontSize * (1 + index));
         });
diff --git a/src/nodes/Node.js b/src/nodes/Node.js
index 9f31ab4..32e7760 100644
--- a/src/nodes/Node.js
+++ b/src/nodes/Node.js
@@ -5,20 +5,28 @@ export default class Node {
 
     constructor(name, inputDefinition, outputDefiniton, options) {
         this.name = name;
+        this.uid = uuidv4();
         this.id = uuidv4();
         this.__in = new Inputs(inputDefinition, this);
         this.__out = new Outputs(outputDefiniton, this);
         this.__in.update = (name) => this.__update([name]);
         this.__scheduledUpdate = false;
+        this.__currentUpdate = Promise.resolve();
+        this._stopped = false;
     }
 
     __update(changes) {
-        if (!this.__scheduledUpdate) {
+        if (!this.__scheduledUpdate && !this._stopped) {
             this.__scheduledUpdate = true;
-            Promise.resolve()
-                .then(() => {
+            this.__currentUpdate = this.__currentUpdate
+                .then(async () => {
+                    const startTag =`graphfx-update-start:${this.uid}`;
+                    const endTag = `graphfx-update-end:${this.uid}`
                     this.__scheduledUpdate = false;
-                    this._update();
+                    performance.mark(startTag)
+                    await this._update();
+                    performance.mark(endTag)
+                    performance.measure(`GraphFX<${this.name}>`, startTag, endTag)
                 });
         }
     }
@@ -57,11 +65,9 @@ export default class Node {
     }
 
     reconnect({options}, outputs) {
-        console.log('outputs', outputs)
         for (let name of Object.keys(options.in)) {
             const {output} = options.in[name];
             if (output) {
-                console.log('connecting', this.in[name].id, outputs[output])
                 this.in[name].connect(outputs[output]);
             }
         }
@@ -69,9 +75,18 @@ export default class Node {
             this.out[name].deserialize(options.out[name]);
         }
         for (let name of Object.keys(options.in)) {
-            console.log(options.in[name]);
             this.in[name].deserialize(options.in[name]);
         }
     }
+
+    destroy() {
+        this._stopped = true;
+        Promise.resolve()
+            .then(() => {
+                for (let input of this.in) {
+                    input.disconnect();
+                }
+            })
+    }
 };
 
diff --git a/src/nodes/WebGL/WebGl.js b/src/nodes/WebGL/WebGl.js
index bea6a37..f5c1e12 100644
--- a/src/nodes/WebGL/WebGl.js
+++ b/src/nodes/WebGL/WebGl.js
@@ -21,6 +21,12 @@ export default class WebGL extends Node {
         });
     }
 
+    destroy() {
+        this.canvas = null;
+        this.program = null;
+        super.destroy();
+    }
+
     get vert() {
         return `
         attribute vec2 a_position;
@@ -147,6 +153,9 @@ export default class WebGL extends Node {
         const image = this.in.image.value;
         if (!image) return;
         const {width, height} = mediaSize(image);
+        if (width === 0 || height === 0) {
+            return;
+        }
         this.setup();
         const canvas = this.canvas;
         canvas.width = width;
@@ -222,8 +231,12 @@ export default class WebGL extends Node {
 
         const result = await createImageBitmap(canvas);
         this.out.image.value = result;
-        this.out.width.value = this.out.image.value.width;
-        this.out.height.value = this.out.image.value.height;
+        if (this.out.width.value !== this.out.image.value.width) {
+            this.out.width.value = this.out.image.value.width;
+        }
+        if (this.out.height.value !== this.out.image.value.height) {
+            this.out.height.value = this.out.image.value.height;
+        }
     }
 
     setRectangle(gl, x, y, width, height) {
diff --git a/src/nodes/Webcam.js b/src/nodes/Webcam.js
index 4c60f75..274724f 100644
--- a/src/nodes/Webcam.js
+++ b/src/nodes/Webcam.js
@@ -1,6 +1,6 @@
 import Node from './Node';
 
-export default class ToBlob extends Node {
+export default class Webcam extends Node {
 
     constructor(options) {
         super('Webcam', {}, {
@@ -14,14 +14,14 @@ export default class ToBlob extends Node {
                 type: 'Number',
             }
         });
-        this.start();
+        this.start()
+            .catch(console.error.bind(console))
     }
 
 
     async start() {
         const devices = (await navigator.mediaDevices.enumerateDevices()).filter((d) => d.kind === 'videoinput')
         const last = (ary) => ary[ary.length - 1];
-        console.log(last(devices));
         const stream = await navigator.mediaDevices.getUserMedia({
             video: {
                 width: { min: 480, ideal: 1920, max: 1920 },
@@ -29,7 +29,6 @@ export default class ToBlob extends Node {
                 deviceId: last(devices).deviceId
             },
         });
-        console.log(stream)
         /** @type {HTMLVideoElement} */
 
         const video = document.createElement('video');
@@ -45,7 +44,11 @@ export default class ToBlob extends Node {
                 this.out.width.value = video.videoWidth;
                 this.out.height.value = video.videoHeight;
             }
-            requestAnimationFrame(feedLoop);
+            if (!this._stopped) {
+                requestAnimationFrame(feedLoop);
+            } else {
+                video.src = null;
+            }
         };
         feedLoop();
     }
diff --git a/src/nodes/io/AbstractIOSet.js b/src/nodes/io/AbstractIOSet.js
index 1ce7c12..0254681 100644
--- a/src/nodes/io/AbstractIOSet.js
+++ b/src/nodes/io/AbstractIOSet.js
@@ -21,6 +21,12 @@ export default class AbstractIOSet {
         }
     }
 
+    *[Symbol.iterator]() {
+        for (let name of Object.keys(this.variables)) {
+            yield this.__values[name];
+        }
+    }
+
     __createProperty(name, definition) {
 
     }
diff --git a/src/utils.js b/src/utils.js
index 695a66f..c028f65 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -9,4 +9,5 @@ export const waitForMedia = async (media) => {
     return media;
 }
 
-export const setImmediate = (fn) => Promise.resolve().then(fn);
\ No newline at end of file
+export const setImmediate = (fn) => Promise.resolve().then(fn);
+