diff --git a/Site/mpw-js/js/dependencies.js b/Site/mpw-js/js/dependencies.js
index dd07cc28..661ae016 100644
--- a/Site/mpw-js/js/dependencies.js
+++ b/Site/mpw-js/js/dependencies.js
@@ -23,6 +23,9 @@ window.TextEncoder || document.write("<script src=js/encoding-polyfill.js><\/scr
 // https://github.com/taylorhakes/promise-polyfill
 window.Promise || document.write("<script src=js/promise-polyfill.js><\/script>");
 
+// If setImmediate is not implemented we include the polyfill
+window.setImmediate || document.write("<script src=js/setImmediate-polyfill.js><\/script>");
+
 // Test for required ES6 features
 // Use an eval call to avoid a hard-fail on ES5 parsers.
 var ES6 = false;
@@ -36,9 +39,6 @@ try {
 // If ES6 is not supported we must include traceur-runtime.js
 ES6 || document.write("<script src=js/mpw-js/traceur-runtime.js><\/script>");
 
-// If setImmediate is not implemented we include the polyfill
-window.setImmediate || document.write("<script src=js/mpw-js/" + esdir + "setImmediate-polyfill.js><\/script>");
-
 // Include the scrypt implementation
 var SCRYPTASM_PATH = (window.location + '').replace(/[^/]*(#[^#]*)?$/, 'js/mpw-js/scrypt-asm.js');
 document.write("<script src=js/mpw-js/" + esdir + "scrypt.js?1><\/script>");
diff --git a/Site/mpw-js/js/mpw-js b/Site/mpw-js/js/mpw-js
index 28a988eb..9566261e 160000
--- a/Site/mpw-js/js/mpw-js
+++ b/Site/mpw-js/js/mpw-js
@@ -1 +1 @@
-Subproject commit 28a988ebe6d1b8052ecc5190b5f9a1fd658b6cf8
+Subproject commit 9566261e5d9815b5974683efc6648a751cfb4014
diff --git a/Site/mpw-js/js/setImmediate-polyfill.js b/Site/mpw-js/js/setImmediate-polyfill.js
new file mode 100644
index 00000000..2bd1ec20
--- /dev/null
+++ b/Site/mpw-js/js/setImmediate-polyfill.js
@@ -0,0 +1,211 @@
+/*! by Tom Thorogood <me@tomthorogood.co.uk> */
+/*! This work is licensed under the Creative Commons Attribution 4.0
+International License. To view a copy of this license, visit
+http://creativecommons.org/licenses/by/4.0/ or see LICENSE. */
+
+// setImmediate is a 0-delay setTimeout of sorts introduced
+// by MS and wrongly held back by other browsers
+window.setImmediate || !function (global) {
+	// Get the global prototype to attach setImmediate to
+	let attachTo = Object.getPrototypeOf && Object.getPrototypeOf(global);
+	
+	// If we couldn't get the prototype or setTimeout wasn't attached
+	// to the prototype we just attach to global
+	attachTo && attachTo.setTimeout || (attachTo = global);
+	
+	// If the MS prefixed implementation exists, use it
+	if (global.msSetImmediate) {
+		return attachTo.setImmediate = global.msSetImmediate, attachTo.clearImmediate = global.msClearImmediate;
+	}
+	
+	// https://github.com/YuzuJS/setImmediate/blob/master/setImmediate.js
+	// This checks if the current environment is Node.js
+	if (global.process && Object.prototype.toString(global.process) === "[object process]") {
+		// If it is we might be able to use timers
+		let timers = global.require("timers");
+		
+		// If it implements setImmediate we use it
+		if (timers && timers.setImmediate) {
+			return attachTo.setImmediate = timers.setImmediate, attachTo.clearImmediate = timers.clearImmediate;
+		}
+		
+		// If it isn't we polyfill with nextTick which is
+		// sufficiently similar
+		if (global.process.nextTick) {
+			return attachTo.setImmediate = function (func, ...params) {
+				// Invoke func with the params as passed into setImmediate
+				global.process.nextTick(() => func(...params));
+			}, attachTo.clearImmediate = function (immediateID) {
+				// There is no id or way to stop nextTick
+				throw new Error("clearImmediate not implemented");
+			};
+		}
+	}
+	
+	// http://dbaron.org/log/20100309-faster-timeouts
+	// https://github.com/YuzuJS/setImmediate/blob/master/setImmediate.js
+	// https://github.com/kriskowal/q/blob/0428c15d2ffc8e874b4be3a50e92884ef8701a6f/q.js#L125-141
+	// If we have messaging channels, or we have postMessage and this
+	// isn't a WebWorker, we can use messaging
+	if (global.MessageChannel || global.postMessage && !global.importScripts && (function () {
+		// This checks if global.postMessage is asynchronous,
+		// it has been known to be buggy and synchronous in
+		// some browsers
+		let postMessageIsAsynchronous = true;
+		let oldOnMessage = global.onmessage;
+		global.onmessage = function () { postMessageIsAsynchronous = false; };
+		global.postMessage("", "*");
+		global.onmessage = oldOnMessage;
+		return postMessageIsAsynchronous;
+	})()) {
+		// A unique id prefix to ensure that ONLY valid messages are accepted
+		let messageName = `setImmediate-polyfill-${Math.random()}`.replace("0.", "");
+		
+		// The numeric identifier of the next dispatched scrypt call
+		let immediateID = 1;
+		
+		// The timeout function and arguments, indexed by numeric identifier
+		let timeouts = { };
+		
+		// If a MessageChannel exists we can use it to avoid sending
+		// messages to the browser which could cause interoperability
+		// issues
+		let channel = global.MessageChannel && new global.MessageChannel();
+		
+		// We need to start port1 in order to receive messages sent
+		// from port2
+		channel && channel.port1.start();
+		
+		// Add a handler to the message event of either the message
+		// channel, if it exists, or global if it does not
+		(channel && channel.port1 || global).addEventListener("message", function (event) {
+			// If event data is not a string, i.e. doesn't implement split,
+			// we didn't send it
+			if (!event.data || !event.data.split) {
+				return;
+			}
+			
+			// Split the identifier into the name and numeric id
+			let [name, immediateID] = event.data.split("$");
+			
+			// If we are not using a MessageChannel check that the source
+			// of the event was this window, also check the name is valid,
+			// if either of these are not true, we didn't send it
+			if (!channel && event.source !== global || name !== messageName) {
+				return;
+			}
+			
+			// Prevent the event from propagating further
+			event.stopPropagation();
+			
+			// Retrieve the function and the arguments we will invoke
+			// leaving func and params as null if the immediateID
+			// does not exist in timeouts (because clearImmediate has
+			// been called before we got here)
+			let [func, params] = timeouts[immediateID] || [ ];
+			
+			// Invoke the func with the appropriate parameters
+			func && func(...params);
+			
+			// Clear func and params for GC
+			func = params = null;
+			
+			// Remove key:immediateID from timeouts to ensure it's only
+			// called once and to allow for GC
+			delete timeouts[immediateID];
+		}, false);
+		
+		return attachTo.setImmediate = function (func, ...params) {
+			// Store the function and it's arguments in timeouts
+			timeouts[immediateID] = [func, params];
+			
+			// Post the message either using port2 of the MessageChannel
+			// or on global if it's not available w/ the unique id
+			// If the message is sent on global we dispatch it w/ a
+			// targetOrigin of "*" (indicating no preference)
+			(channel && channel.port2 || global).postMessage([messageName, immediateID].join("$"), ...(channel ? [ ] : ["*"]));
+			
+			// We return a unique numeric id to identify the call
+			// to setImmediate, this allows it to be cancelled
+			return immediateID++;
+		}, attachTo.clearImmediate = function (immediateID) {
+			// Delete the function and arguments associated
+			// w/ identifier of immediateID
+			delete timeouts[immediateID];
+		};
+	}
+	
+	// Set setImmediate to prefixed or non-prefixed requestAnimationFrame
+	// requestAnimationFrame dispatches at a later point in the event cycle
+	attachTo.setImmediate = global.requestAnimationFrame || global.mozRequestAnimationFrame || global.webkitRequestAnimationFrame || global.msRequestAnimationFrame;
+	
+	// If requestAnimationFrame existed we end, setting clearImmediate
+	// to cancelAnimationFrame
+	if (attachTo.setImmediate) {
+		return attachTo.clearImmediate = global.cancelAnimationFrame || global.mozCancelAnimationFrame || global.webkitCancelAnimationFrame || global.msCancelAnimationFrame || global.webkitCancelRequestAnimationFrame;
+	}
+	
+	// https://github.com/YuzuJS/setImmediate/blob/master/setImmediate.js
+	// We can use a script tag and the readystatechange event on IE(?)
+	if (global.document && "onreadystatechange" in global.document.getElementsByTagName("script")[0]) {
+		// The numeric identifier of the next dispatched scrypt call
+		let immediateID = 1;
+		
+		// A boolean value to allow clearImmediate to work,
+		// indexed by numeric identifier
+		let timeouts = { };
+		
+		return attachTo.setImmediate = function (func, ...params) {
+			// Set true in timeouts for immediateID to indicate the func
+			// should be invoked
+			timeouts[immediateID] = true;
+			
+			// Create a script tag that will be added to the DOM
+			let script = global.document.createElement("script");
+			
+			// Add a handler for onreadystatechange
+			script.onreadystatechange = function () {
+				// If the timeout has not been cancelled, call the func
+				// w/ the arguments specified
+				timeouts[immediateID] && func(...params);
+				
+				// Remove key:immediateID from timeouts to ensure it's only called once 
+				delete timeouts[immediateID];
+				
+				// Remove the handler to allow GC
+				script.onreadystatechange = null;
+				
+				// Remove the script tag from the DOM to ensure GC
+				global.document.body.removeChild(script);
+				
+				// Nullify the script variable to allow GC
+				script = null;
+			};
+			
+			// Add the script tag to the DOM to which begins loading
+			// the tag which will invoke the readystatechange event
+			global.document.body.appendChild(script);
+			
+			// Return a unique numeric id to identify the call
+			// to setImmediate, this allows it to be cancelled
+			return immediateID++;
+		}, attachTo.clearImmediate = function (immediateID) {
+			// Remove key:immediateID from timeouts to prevent func from being called
+			delete timeouts[immediateID];
+		};
+	}
+	
+	// The worst fallback is setImmediate, although the delay is set to 0
+	// in reality this should have a ~20ms delay, this is an important part
+	// of the spec
+	attachTo.setImmediate = (func, ...params) => global.setTimeout(func, 0, ...params);
+	attachTo.clearImmediate = global.clearTimeout;
+	
+	// Here we check if the arguments passed to setTimeout actually will be
+	// passed to the callback, on older versions of IE(?) this check will fail
+	global.setTimeout(function (arg) {
+		// If the test fails, we wrap func in a closure that will invoke func w/
+		// the arguments
+		arg || (attachTo.setImmediate = (func, ...params) => global.setTimeout(() => func(...params), 0));
+	}, 0, true);
+}(this);
\ No newline at end of file