diff --git a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.html b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.html
index fab0425..6e7a68a 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.html
@@ -129,7 +129,7 @@
           class="editMessage"
           disabled="{{disabled}}"
           rows="4"
-          bind-value="{{_editDraft}}"
+          bind-value="{{_messageText}}"
           on-keydown="_handleTextareaKeydown"></iron-autogrow-textarea>
       <gr-linked-text class="message"
           pre
@@ -141,7 +141,7 @@
         <gr-button class="action done" on-tap="_handleDone">Done</gr-button>
         <gr-button class="action edit" on-tap="_handleEdit">Edit</gr-button>
         <gr-button class="action save" on-tap="_handleSave"
-            disabled$="[[_computeSaveDisabled(_editDraft)]]">Save</gr-button>
+            disabled$="[[_computeSaveDisabled(_messageText)]]">Save</gr-button>
         <gr-button class="action cancel" on-tap="_handleCancel" hidden>Cancel</gr-button>
         <div class="danger">
           <gr-button class="action discard" on-tap="_handleDiscard">Discard</gr-button>
@@ -149,7 +149,7 @@
       </div>
     </div>
     <gr-rest-api-interface id="restAPI"></gr-rest-api-interface>
-    <gr-storage id="localStorage"></gr-storage>
+    <gr-storage id="storage"></gr-storage>
   </template>
   <script src="gr-diff-comment.js"></script>
 </dom-module>
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js
index c28d0ac..f7b5f01 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js
@@ -69,25 +69,29 @@
       projectConfig: Object,
 
       _xhrPromise: Object,  // Used for testing.
-      _editDraft: {
+      _messageText: {
         type: String,
-        observer: '_editDraftChanged',
+        observer: '_messageTextChanged',
       },
     },
 
     ready: function() {
       this._loadLocalDraft().then(function(loadedLocal) {
-        this._editDraft = (this.comment && this.comment.message) || '';
-        this.editing = !this._editDraft.length || loadedLocal;
+        this._messageText = (this.comment && this.comment.message) || '';
+        this.editing = !this._messageText.length || loadedLocal;
       }.bind(this));
     },
 
     save: function() {
-      this.comment.message = this._editDraft;
+      this.comment.message = this._messageText;
       this.disabled = true;
 
-      this.$.localStorage.eraseDraft(this.changeNum, this.patchNum,
-          this.comment.path, this.comment.line);
+      this.$.storage.eraseDraftComment({
+        changeNum: this.changeNum,
+        patchNum: this.patchNum,
+        path: this.comment.path,
+        line: this.comment.line,
+      });
 
       this._xhrPromise = this._saveDraft(this.comment).then(function(response) {
         this.disabled = false;
@@ -147,23 +151,27 @@
       }
     },
 
-    _editDraftChanged: function(newValue, oldValue) {
+    _messageTextChanged: function(newValue, oldValue) {
       if (this.comment && this.comment.id) { return; }
 
       this.debounce('store', function() {
-        var message = this._editDraft;
+        var message = this._messageText;
 
-        // If the draft has been modified to be empty, then erase the storage
-        // entry.
-        if ((!this._editDraft || !this._editDraft.length) && oldValue) {
-          this.$.localStorage.eraseDraft(this.changeNum, this.patchNum,
-              this.comment.path, this.comment.line);
-          return;
+        var commentLocation = {
+          changeNum: this.changeNum,
+          patchNum: this.patchNum,
+          path: this.comment.path,
+          line: this.comment.line,
+        };
+
+        if ((!this._messageText || !this._messageText.length) && oldValue) {
+          // If the draft has been modified to be empty, then erase the storage
+          // entry.
+          this.$.storage.eraseDraftComment(commentLocation);
+        } else {
+          this.$.storage.setDraftComment(commentLocation, message);
         }
-
-        this.$.localStorage.setDraft(this.changeNum, this.patchNum,
-            this.comment.path, this.comment.line, message);
-      }.bind(this), STORAGE_DEBOUNCE_INTERVAL);
+      }, STORAGE_DEBOUNCE_INTERVAL);
     },
 
     _handleLinkTap: function(e) {
@@ -195,7 +203,7 @@
 
     _handleEdit: function(e) {
       this._preventDefaultAndBlur(e);
-      this._editDraft = this.comment.message;
+      this._messageText = this.comment.message;
       this.editing = true;
     },
 
@@ -210,7 +218,7 @@
         this.fire('comment-discard');
         return;
       }
-      this._editDraft = this.comment.message;
+      this._messageText = this.comment.message;
       this.editing = false;
     },
 
@@ -252,6 +260,8 @@
     },
 
     _loadLocalDraft: function() {
+      // Use an async promise to avoid blocking render on potentially slow
+      // localStorage calls.
       return new Promise(function(resolve) {
         this.async(function() {
           // Only apply local drafts to comments that haven't been saved
@@ -261,8 +271,12 @@
             return;
           }
 
-          var draft = this.$.localStorage.getDraft(this.changeNum,
-              this.patchNum, this.comment.path, this.comment.line);
+          var draft = this.$.storage.getDraftComment({
+            changeNum: this.changeNum,
+            patchNum: this.patchNum,
+            path: this.comment.path,
+            line: this.comment.line,
+          });
 
           if (draft) {
             this.comment.message = draft.message;
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html
index a333e14..8ef222e 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html
@@ -183,11 +183,11 @@
       MockInteractions.tap(element.$$('.edit'));
       assert.isTrue(element.editing);
 
-      element._editDraft = '';
+      element._messageText = '';
       // Save should be disabled on an empty message.
       var disabled = element.$$('.save').hasAttribute('disabled');
       assert.isTrue(disabled, 'save button should be disabled.');
-      element._editDraft = '     ';
+      element._messageText = '     ';
       disabled = element.$$('.save').hasAttribute('disabled');
       assert.isTrue(disabled, 'save button should be disabled.');
 
@@ -206,7 +206,7 @@
     test('draft saving/editing', function(done) {
       element.draft = true;
       MockInteractions.tap(element.$$('.edit'));
-      element._editDraft = 'good news, everyone!';
+      element._messageText = 'good news, everyone!';
       MockInteractions.tap(element.$$('.save'));
       assert.isTrue(element.disabled,
           'Element should be disabled when creating draft.');
@@ -218,7 +218,7 @@
         assert.isFalse(element.editing);
       }).then(function() {
         MockInteractions.tap(element.$$('.edit'));
-        element._editDraft = 'You’ll be delivering a package to Chapek 9, a ' +
+        element._messageText = 'You’ll be delivering a package to Chapek 9, a ' +
             'world where humans are killed on sight.';
         MockInteractions.tap(element.$$('.save'));
         assert.isTrue(element.disabled,
diff --git a/polygerrit-ui/app/elements/shared/gr-storage/gr-storage.html b/polygerrit-ui/app/elements/shared/gr-storage/gr-storage.html
index e877aec..74bfcdf 100644
--- a/polygerrit-ui/app/elements/shared/gr-storage/gr-storage.html
+++ b/polygerrit-ui/app/elements/shared/gr-storage/gr-storage.html
@@ -15,6 +15,5 @@
 -->
 <link rel="import" href="../../../bower_components/polymer/polymer.html">
 <dom-module id="gr-storage">
-  <template></template>
   <script src="gr-storage.js"></script>
 </dom-module>
diff --git a/polygerrit-ui/app/elements/shared/gr-storage/gr-storage.js b/polygerrit-ui/app/elements/shared/gr-storage/gr-storage.js
index 79012d4..ef3a6c0 100644
--- a/polygerrit-ui/app/elements/shared/gr-storage/gr-storage.js
+++ b/polygerrit-ui/app/elements/shared/gr-storage/gr-storage.js
@@ -17,10 +17,14 @@
   // Date cutoff is one day:
   var DRAFT_MAX_AGE = 24*60*60*1000;
 
+  // Clean up old entries no more frequently than one day.
+  var CLEANUP_THROTTLE_INTERVAL = 24*60*60*1000;
+
   Polymer({
     is: 'gr-storage',
 
     properties: {
+      _lastCleanup: Number,
       _storage: {
         type: Object,
         value: function() {
@@ -29,27 +33,34 @@
       },
     },
 
-    getDraft: function(changeNum, patchNum, path, line) {
+    getDraftComment: function(location) {
       this._cleanupDrafts();
-      return this._getObject(
-          this._getDraftKey(changeNum, patchNum, path, line));
+      return this._getObject(this._getDraftKey(location));
     },
 
-    setDraft: function(changeNum, patchNum, path, line, message) {
-      var key = this._getDraftKey(changeNum, patchNum, path, line);
+    setDraftComment: function(location, message) {
+      var key = this._getDraftKey(location);
       this._setObject(key, {message: message, updated: Date.now()});
     },
 
-    eraseDraft: function(changeNum, patchNum, path, line) {
-      var key = this._getDraftKey(changeNum, patchNum, path, line);
+    eraseDraftComment: function(location) {
+      var key = this._getDraftKey(location);
       this._storage.removeItem(key);
     },
 
-    _getDraftKey: function(changeNum, patchNum, path, line) {
-      return ['draft', changeNum, patchNum, path, line].join(':');
+    _getDraftKey: function(location) {
+      return ['draft', location.changeNum, location.patchNum, location.path,
+          location.line].join(':');
     },
 
     _cleanupDrafts: function() {
+      // Throttle cleanup to the throttle interval.
+      if (this._lastCleanup &&
+          Date.now() - this._lastCleanup < CLEANUP_THROTTLE_INTERVAL) {
+        return;
+      }
+      this._lastCleanup = Date.now();
+
       var draft;
       for (var key in this._storage) {
         if (key.indexOf('draft:') === 0) {
diff --git a/polygerrit-ui/app/elements/shared/gr-storage/gr-storage_test.html b/polygerrit-ui/app/elements/shared/gr-storage/gr-storage_test.html
index d21a6c4..4e17cb6 100644
--- a/polygerrit-ui/app/elements/shared/gr-storage/gr-storage_test.html
+++ b/polygerrit-ui/app/elements/shared/gr-storage/gr-storage_test.html
@@ -51,23 +51,29 @@
       var patchNum = 5;
       var path = 'my_source_file.js';
       var line = 123;
+      var location = {
+        changeNum: changeNum,
+        patchNum: patchNum,
+        path: path,
+        line: line,
+      };
 
       // The key is in the expected format.
-      var key = element._getDraftKey(changeNum, patchNum, path, line);
+      var key = element._getDraftKey(location);
       assert.equal(key, ['draft', changeNum, patchNum, path, line].join(':'));
 
       // There should be no draft initially.
-      var draft = element.getDraft(changeNum, patchNum, path, line);
+      var draft = element.getDraftComment(location);
       assert.isNotOk(draft);
 
       // Setting the draft stores it under the expected key.
-      element.setDraft(changeNum, patchNum, path, line, 'my comment');
+      element.setDraftComment(location, 'my comment');
       assert.isOk(storage.getItem(key));
       assert.equal(JSON.parse(storage.getItem(key)).message, 'my comment');
       assert.isOk(JSON.parse(storage.getItem(key)).updated);
 
       // Erasing the draft removes the key.
-      element.eraseDraft(changeNum, patchNum, path, line);
+      element.eraseDraftComment(location);
       assert.isNotOk(storage.getItem(key));
 
       cleanupStorage();
@@ -78,7 +84,16 @@
       var patchNum = 5;
       var path = 'my_source_file.js';
       var line = 123;
-      var key = element._getDraftKey(changeNum, patchNum, path, line);
+      var location = {
+        changeNum: changeNum,
+        patchNum: patchNum,
+        path: path,
+        line: line,
+      };
+      var key = element._getDraftKey(location);
+
+      // Make sure that the call to cleanup doesn't get throttled.
+      element._lastCleanup = 0;
 
       var cleanupSpy = sinon.spy(element, '_cleanupDrafts');
 
@@ -89,7 +104,7 @@
       }));
 
       // Getting the draft should cause it to be removed.
-      var draft = element.getDraft(changeNum, patchNum, path, line);
+      var draft = element.getDraftComment(location);
 
       assert.isTrue(cleanupSpy.called);
       assert.isNotOk(draft);