diff --git a/www/code/inner.html b/www/code/inner.html
index 6fad16db8..80d1cb707 100644
--- a/www/code/inner.html
+++ b/www/code/inner.html
@@ -2,7 +2,7 @@
 <html class="cp-app-noscroll">
 <head>
     <meta content="text/html; charset=utf-8" http-equiv="content-type"/>
-    <script async data-bootload="/code/inner.js" data-main="/common/sframe-boot.js?ver=1.1" src="/bower_components/requirejs/require.js?ver=2.3.5"></script>
+    <script async data-bootload="/code/inner.js" data-main="/common/sframe-boot.js?ver=1.3" src="/bower_components/requirejs/require.js?ver=2.3.5"></script>
     <style>
         .loading-hidden { display: none; }
         #editor1 { display: none; }
diff --git a/www/common/LessLoader.js b/www/common/LessLoader.js
index c7b015655..36cb47d49 100644
--- a/www/common/LessLoader.js
+++ b/www/common/LessLoader.js
@@ -1,23 +1,38 @@
 /*@flow*/
 /*:: const define = () => {}; */
 define([
-    '/api/config',
-    '/bower_components/less/dist/less.min.js'
-], function (Config, Less) { /*::});module.exports = (function() {
+    '/api/config'
+], function (Config) { /*::});module.exports = (function() {
     const Config = (undefined:any);
-    const Less = (undefined:any);
     */
 
     var module = { exports: {} };
     var key = Config.requireConf.urlArgs;
-    var localStorage;
+    var localStorage = {};
     try {
         localStorage = window.localStorage || {};
+        if (localStorage['LESS_CACHE'] !== key) {
+            Object.keys(localStorage).forEach(function (k) {
+                if (k.indexOf('LESS_CACHE|') !== 0) { return; }
+                delete localStorage[k];
+            });
+            localStorage['LESS_CACHE'] = key;
+        }
     } catch (e) {
         console.error(e);
         localStorage = {};
     }
 
+    var cacheGet = function (k, cb) {
+        if (window.cryptpadCache) { return void window.cryptpadCache.get(k, cb); }
+        setTimeout(function () { cb(localStorage['LESS_CACHE|' + key + '|' + k]); })
+    };
+    var cachePut = function (k, v, cb) {
+        if (window.cryptpadCache) { return void window.cryptpadCache.put(k, v, cb); }
+        cb = cb || function () { };
+        setTimeout(function () { localStorage['LESS_CACHE|' + key + '|' + k] = v; cb(); });
+    };
+
     var fixURL = function (url, parent) {
         // data: blob: etc
         if (/^[a-zA-Z0-9]*:/.test(url)) { return url; }
@@ -32,13 +47,6 @@ define([
         return out;
     };
 
-    var doXHR = Less.FileManager.prototype.doXHR;
-    Less.FileManager.prototype.doXHR = function (url, type, callback, errback) {
-        url = fixURL(url);
-        //console.log("xhr: " + url);
-        return doXHR(url, type, callback, errback);
-    };
-
     var inject = function (cssText, url) {
         var curStyle = document.createElement('style');
         curStyle.setAttribute('data-original-src', url);
@@ -48,15 +56,6 @@ define([
         document.head.appendChild(curStyle);
     };
 
-    var checkCache = function () {
-        if (localStorage['LESS_CACHE'] === key) { return; }
-        Object.keys(localStorage).forEach(function (k) {
-            if (k.indexOf('LESS_CACHE|') !== 0) { return; }
-            delete localStorage[k];
-        });
-        localStorage['LESS_CACHE'] = key;
-    };
-
     var fixAllURLs = function (source, parent) {
         var urlRegEx = /@import\s*("([^"]*)"|'([^']*)')|url\s*\(\s*(\s*"([^"]*)"|'([^']*)'|[^\)]*\s*)\s*\)/ig;
         var result, url;
@@ -84,25 +83,46 @@ define([
         xhr.send(null);
     };
 
+    var lessEngine;
+    var getLessEngine = function (cb) {
+        if (lessEngine) {
+            cb(lessEngine);
+        } else {
+            require(['/bower_components/less/dist/less.min.js'], function (Less) {
+                lessEngine = Less;
+                var doXHR = lessEngine.FileManager.prototype.doXHR;
+                lessEngine.FileManager.prototype.doXHR = function (url, type, callback, errback) {
+                    url = fixURL(url);
+                    //console.log("xhr: " + url);
+                    return doXHR(url, type, callback, errback);
+                };
+                cb(lessEngine);
+            });
+        }
+    };
+
     var loadLess = function (url, cb) {
-        Less.render('@import (multiple) "' + url + '";', {}, function(err, css) {
-            if (err) { return void cb(err); }
-            cb(undefined, css.css);
-        }, window.less);
+        getLessEngine(function (less) {
+            less.render('@import (multiple) "' + url + '";', {}, function(err, css) {
+                if (err) { return void cb(err); }
+                cb(undefined, css.css);
+            }, window.less);
+        });
     };
 
     module.exports.load = function (url /*:string*/, cb /*:()=>void*/) {
-        checkCache();
-        if (localStorage['LESS_CACHE|' + key + '|' + url]) {
-            inject(localStorage['LESS_CACHE|' + key + '|' + url], url);
-            cb();
-            return;
-        }
-        ((/\.less([\?\#].*)?$/.test(url)) ? loadLess : loadCSS)(url, function (err, css) {
-            var output = fixAllURLs(css, url);
-            localStorage['LESS_CACHE|' + key + '|' + url] = output;
-            inject(output, url);
-            cb();
+        cacheGet(url, function (css) {
+            if (css) {
+                inject(css, url);
+                return void cb();
+            }
+            console.log('CACHE MISS ' + url);
+            ((/\.less([\?\#].*)?$/.test(url)) ? loadLess : loadCSS)(url, function (err, css) {
+                var output = fixAllURLs(css, url);
+                cachePut(url, output);
+                inject(output, url);
+                cb();
+            });
         });
     };
 
diff --git a/www/common/sframe-boot.js b/www/common/sframe-boot.js
index 2ff9762b6..4489db89f 100644
--- a/www/common/sframe-boot.js
+++ b/www/common/sframe-boot.js
@@ -1,7 +1,37 @@
 // Stage 0, this gets cached which means we can't change it. boot2-sframe.js is changable.
 // Note that this file is meant to be executed only inside of a sandbox iframe.
+//
+// IF YOU EDIT THIS FILE, bump the version (replace 1.3 in the following command with the next version.)
+// grep -nr '/common/sframe-boot.js?ver=' | sed 's/:.*$//' | while read x; do \
+//    sed -i -e 's@/common/sframe-boot.js?ver=[^"]*@/common/sframe-boot.js?ver=1.3@' $x; done
 ;(function () {
 var afterLoaded = function (req) {
+    var localStorage = {};
+    if (req.cfg && req.cfg.urlArgs) {
+        try {
+            localStorage = window.localStorage;
+            if (localStorage['CRYPTPAD_VERSION'] !== req.cfg.urlArgs) {
+                // new version, flush
+                Object.keys(localStorage).forEach(function (k) {
+                    if (!k.indexOf('CRYPTPAD_CACHE_')) { delete localStorage[k]; }
+                });
+                localStorage['CRYPTPAD_VERSION'] = req.cfg.urlArgs;
+            }
+        } catch (e) {
+            console.error(e);
+            localStorage = {};
+        }
+    }
+    window.cryptpadCache = Object.freeze({
+        put: function (k, v, cb) {
+            cb = cb || function () { };
+            setTimeout(function () { localStorage['CRYPTPAD_CACHE_' + k] = v; cb(); });
+        },
+        get: function (k, cb) {
+            if (!cb) { throw new Error(); }
+            setTimeout(function () { cb(localStorage['CRYPTPAD_CACHE_' + k]); });
+        }
+    });
     req.cfg = req.cfg || {};
     if (req.pfx) {
         req.cfg.onNodeCreated = function (node /*, config, module, path*/) {
diff --git a/www/common/sframe-boot2.js b/www/common/sframe-boot2.js
index 38395a21f..e6845bcbe 100644
--- a/www/common/sframe-boot2.js
+++ b/www/common/sframe-boot2.js
@@ -10,17 +10,6 @@ define(['/common/requireconfig.js'], function (RequireConfig) {
         };
     }
 
-    // In the event that someone clicks a link in the iframe, it's going to cause the iframe
-    // to navigate away from the pad which is going to be a mess. Instead we'll just reload
-    // the top level and then it will be simply that a link doesn't work properly.
-    window.onunload = function () {
-        window.parent.location.reload();
-    };
-
-    // Make sure anything which might have leaked to the localstorage is always cleaned up.
-    try { window.localStorage.clear(); } catch (e) { }
-    try { window.sessionStorage.clear(); } catch (e) { }
-
     var mkFakeStore = function () {
         var fakeStorage = {
             getItem: function (k) { return fakeStorage[k]; },
diff --git a/www/file/inner.html b/www/file/inner.html
index f43c1e73e..3fce59ddd 100644
--- a/www/file/inner.html
+++ b/www/file/inner.html
@@ -2,7 +2,7 @@
 <html class="cp-app-noscroll">
 <head>
     <meta content="text/html; charset=utf-8" http-equiv="content-type"/>
-    <script async data-bootload="/file/inner.js" data-main="/common/sframe-boot.js?ver=1.1" src="/bower_components/requirejs/require.js?ver=2.3.5"></script>
+    <script async data-bootload="/file/inner.js" data-main="/common/sframe-boot.js?ver=1.3" src="/bower_components/requirejs/require.js?ver=2.3.5"></script>
     <style>
         .loading-hidden { display: none; }
         #editor1 { display: none; }
diff --git a/www/filepicker/inner.html b/www/filepicker/inner.html
index bad6fb1b0..ae94b6ce7 100644
--- a/www/filepicker/inner.html
+++ b/www/filepicker/inner.html
@@ -2,7 +2,7 @@
 <html style="height: 100%; background: transparent;">
 <head>
     <meta content="text/html; charset=utf-8" http-equiv="content-type"/>
-    <script async data-bootload="/filepicker/inner.js" data-main="/common/sframe-boot.js?ver=1.1" src="/bower_components/requirejs/require.js?ver=2.3.5"></script>
+    <script async data-bootload="/filepicker/inner.js" data-main="/common/sframe-boot.js?ver=1.3" src="/bower_components/requirejs/require.js?ver=2.3.5"></script>
     <style>
         .loading-hidden { display: none; }
         body #loading {
diff --git a/www/pad/inner.html b/www/pad/inner.html
index 4a45b3716..b9b87c58e 100644
--- a/www/pad/inner.html
+++ b/www/pad/inner.html
@@ -2,7 +2,7 @@
 <html class="cp-app-noscroll">
 <head>
     <meta content="text/html; charset=utf-8" http-equiv="content-type"/>
-    <script async data-bootload="/pad/inner.js" data-main="/common/sframe-boot.js?ver=1.2" src="/bower_components/requirejs/require.js?ver=2.3.5"></script>
+    <script async data-bootload="/pad/inner.js" data-main="/common/sframe-boot.js?ver=1.3" src="/bower_components/requirejs/require.js?ver=2.3.5"></script>
 </head>
 <body class="cp-app-pad">
     <textarea style="display:none" id="editor1" name="editor1"></textarea>
diff --git a/www/slide/inner.html b/www/slide/inner.html
index 8ba4311e8..5ebacbb14 100644
--- a/www/slide/inner.html
+++ b/www/slide/inner.html
@@ -2,7 +2,7 @@
 <html class="cp-app-noscroll cp-app-print">
 <head>
     <meta content="text/html; charset=utf-8" http-equiv="content-type"/>
-    <script async data-bootload="/slide/inner.js" data-main="/common/sframe-boot.js?ver=1.1" src="/bower_components/requirejs/require.js?ver=2.3.5"></script>
+    <script async data-bootload="/slide/inner.js" data-main="/common/sframe-boot.js?ver=1.3" src="/bower_components/requirejs/require.js?ver=2.3.5"></script>
     <style>
         .loading-hidden { display: none; }
         #editor1 { display: none; }
