diff --git a/app.js b/app.js
index b3473a13e..86df10105 100644
--- a/app.js
+++ b/app.js
@@ -22,6 +22,7 @@ var i18n = require('i18n');
 var config = require("./lib/config.js");
 var logger = require("./lib/logger.js");
 var auth = require("./lib/auth.js");
+var history = require("./lib/history.js");
 var response = require("./lib/response.js");
 var models = require("./lib/models");
 
@@ -365,56 +366,9 @@ app.get('/logout', function (req, res) {
     res.redirect(config.serverurl + '/');
 });
 //get history
-app.get('/history', function (req, res) {
-    if (req.isAuthenticated()) {
-        models.User.findOne({
-            where: {
-                id: req.user.id
-            }
-        }).then(function (user) {
-            if (!user)
-                return response.errorNotFound(res);
-            var history = [];
-            if (user.history)
-                history = JSON.parse(user.history);
-            res.send({
-                history: history
-            });
-            if (config.debug)
-                logger.info('read history success: ' + user.id);
-        }).catch(function (err) {
-            logger.error('read history failed: ' + err);
-            return response.errorInternalError(res);
-        });
-    } else {
-        return response.errorForbidden(res);
-    }
-});
+app.get('/history', history.historyGet);
 //post history
-app.post('/history', urlencodedParser, function (req, res) {
-    if (req.isAuthenticated()) {
-        if (config.debug)
-            logger.info('SERVER received history from [' + req.user.id + ']: ' + req.body.history);
-        models.User.update({
-            history: req.body.history
-        }, {
-            where: {
-                id: req.user.id
-            }
-        }).then(function (count) {
-            if (!count)
-                return response.errorNotFound(res);
-            if (config.debug)
-                logger.info("write user history success: " + req.user.id);
-        }).catch(function (err) {
-            logger.error('write history failed: ' + err);
-            return response.errorInternalError(res);
-        });
-        res.end();
-    } else {
-        return response.errorForbidden(res);
-    }
-});
+app.post('/history', urlencodedParser, history.historyPost);
 //get me info
 app.get('/me', function (req, res) {
     if (req.isAuthenticated()) {
@@ -522,7 +476,7 @@ function startListen() {
 // sync db then start listen
 models.sequelize.sync().then(function () {
     // check if realtime is ready
-    if (realtime.isReady()) {
+    if (history.isReady() && realtime.isReady()) {
         models.Revision.checkAllNotesRevision(function (err, notes) {
             if (err) return new Error(err);
             if (!notes || notes.length <= 0) return startListen();
@@ -549,7 +503,7 @@ process.on('SIGINT', function () {
         socket.disconnect(true);
     });
     var checkCleanTimer = setInterval(function () {
-        if (realtime.isReady()) {
+        if (history.isReady() && realtime.isReady()) {
             models.Revision.checkAllNotesRevision(function (err, notes) {
                 if (err) return new Error(err);
                 if (notes.length <= 0) {
diff --git a/lib/history.js b/lib/history.js
new file mode 100644
index 000000000..119b75105
--- /dev/null
+++ b/lib/history.js
@@ -0,0 +1,228 @@
+//history
+//external modules
+var async = require('async');
+var moment = require('moment');
+
+//core
+var config = require("./config.js");
+var logger = require("./logger.js");
+var response = require("./response.js");
+var models = require("./models");
+
+//public
+var History = {
+    historyGet: historyGet,
+    historyPost: historyPost,
+    historyDelete: historyDelete,
+    isReady: isReady,
+    updateHistory: updateHistory
+};
+
+var caches = {};
+//update when the history is dirty
+var updater = setInterval(function () {
+    var deleted = [];
+    async.each(Object.keys(caches), function (key, callback) {
+        var cache = caches[key];
+        if (cache.isDirty) {
+            if (config.debug) logger.info("history updater found dirty history: " + key);
+            var history = parseHistoryToArray(cache.history);
+            finishUpdateHistory(key, history, function (err, count) {
+                if (err) return callback(err, null);
+                if (!count) return callback(null, null);
+                cache.isDirty = false;
+                cache.updateAt = Date.now();
+                return callback(null, null);
+            });
+        } else {
+            if (moment().isAfter(moment(cache.updateAt).add(5, 'minutes'))) {
+                deleted.push(key);
+            }
+            return callback(null, null);
+        }
+    }, function (err) {
+        if (err) return logger.error('history updater error', err);
+    });
+    // delete specified caches
+    for (var i = 0, l = deleted.length; i < l; i++) {
+        caches[deleted[i]].history = {};
+        delete caches[deleted[i]];
+    }
+}, 1000);
+
+function finishUpdateHistory(userid, history, callback) {
+    models.User.update({
+        history: JSON.stringify(history)
+    }, {
+        where: {
+            id: userid
+        }
+    }).then(function (count) {
+        return callback(null, count);
+    }).catch(function (err) {
+        return callback(err, null);
+    });
+}
+
+function isReady() {
+    var dirtyCount = 0;
+    async.each(Object.keys(caches), function (key, callback) {
+        if (caches[key].isDirty) dirtyCount++;
+        return callback(null, null);
+    }, function (err) {
+        if (err) return logger.error('history ready check error', err);
+    });
+    return dirtyCount > 0 ? false : true;
+}
+
+function getHistory(userid, callback) {
+    if (caches[userid]) {
+        return callback(null, caches[userid].history);
+    } else {
+        models.User.findOne({
+            where: {
+                id: userid
+            }
+        }).then(function (user) {
+            if (!user)
+                return callback(null, null);
+            var history = [];
+            if (user.history)
+                history = JSON.parse(user.history);
+            if (config.debug)
+                logger.info('read history success: ' + user.id);
+            setHistory(userid, history);
+            return callback(null, history);
+        }).catch(function (err) {
+            logger.error('read history failed: ' + err);
+            return callback(err, null);
+        });   
+    }
+}
+
+function setHistory(userid, history) {
+    if (Array.isArray(history)) history = parseHistoryToObject(history);
+    if (!caches[userid]) {
+        caches[userid] = {
+            history: {},
+            isDirty: false,
+            updateAt: Date.now()
+        };
+    }
+    caches[userid].history = history;
+}
+
+function updateHistory(userid, noteId, document) {
+    var t0 = new Date().getTime();
+    if (userid && noteId && document) {
+        getHistory(userid, function (err, history) {
+            if (err || !history) return;
+            if (!caches[userid].history[noteId]) {
+                caches[userid].history[noteId] = {};
+            }
+            var noteHistory = caches[userid].history[noteId];
+            var noteInfo = models.Note.parseNoteInfo(document);
+            noteHistory.id = noteId;
+            noteHistory.text = noteInfo.title;
+            noteHistory.time = moment().format('MMMM Do YYYY, h:mm:ss a');
+            noteHistory.tags = noteInfo.tags;
+            caches[userid].isDirty = true;
+            var t1 = new Date().getTime();
+            console.warn(t1 - t0);
+        });
+    }
+}
+
+function parseHistoryToArray(history) {
+    var _history = [];
+    Object.keys(history).forEach(function (key) {
+        var item = history[key];
+        _history.push(item);
+    });
+    return _history;
+}
+
+function parseHistoryToObject(history) {
+    var _history = {};
+    for (var i = 0, l = history.length; i < l; i++) {
+        var item = history[i];
+        _history[item.id] = item;
+    }
+    return _history;
+}
+
+function historyGet(req, res) {
+    if (req.isAuthenticated()) {
+        getHistory(req.user.id, function (err, history) {
+            if (err) return response.errorInternalError(res);
+            if (!history) return response.errorNotFound(res);
+            res.send({
+                history: parseHistoryToArray(history)
+            });
+        });
+    } else {
+        return response.errorForbidden(res);
+    }
+}
+
+function historyPost(req, res) {
+    if (req.isAuthenticated()) {
+        var noteId = req.params.noteId;
+        if (!noteId) {
+            if (typeof req.body['history'] === 'undefined') return response.errorBadRequest(res);
+            if (config.debug)
+                logger.info('SERVER received history from [' + req.user.id + ']: ' + req.body.history);
+            try {
+                var history = JSON.parse(req.body.history);
+            } catch (err) {
+                return response.errorBadRequest(res);
+            }
+            if (Array.isArray(history)) {
+                setHistory(req.user.id, history);
+                caches[req.user.id].isDirty = true;
+                res.end();
+            } else {
+                return response.errorBadRequest(res);
+            }
+        } else {
+            if (typeof req.body['pinned'] === 'undefined') return response.errorBadRequest(res);
+            getHistory(req.user.id, function (err, history) {
+                if (err) return response.errorInternalError(res);
+                if (!history) return response.errorNotFound(res);
+                if (!caches[req.user.id].history[noteId]) return response.errorNotFound(res);
+                if (req.body.pinned === 'true' || req.body.pinned === 'false') {
+                    caches[req.user.id].history[noteId].pinned = (req.body.pinned === 'true');
+                    caches[req.user.id].isDirty = true;
+                    res.end();
+                } else {
+                    return response.errorBadRequest(res);
+                }
+            });
+        }
+    } else {
+        return response.errorForbidden(res);
+    }
+}
+
+function historyDelete(req, res) {
+    if (req.isAuthenticated()) {
+        var noteId = req.params.noteId;
+        if (!noteId) {
+            setHistory(req.user.id, []);
+            caches[req.user.id].isDirty = true;
+            res.end();
+        } else {
+            getHistory(req.user.id, function (err, history) {
+                if (err) return response.errorInternalError(res);
+                if (!history) return response.errorNotFound(res);
+                delete caches[req.user.id].history[noteId];
+                caches[req.user.id].isDirty = true;
+                res.end();
+            });
+        }
+    } else {
+        return response.errorForbidden(res);
+    }
+}
+
+module.exports = History;
\ No newline at end of file