diff --git a/src/BackgroundTokenizer.js b/src/BackgroundTokenizer.js
index d9cfe1f6..560d7a8b 100644
--- a/src/BackgroundTokenizer.js
+++ b/src/BackgroundTokenizer.js
@@ -73,7 +73,7 @@ ace.BackgroundTokenizer.prototype.start = function(startRow) {
 
     if (!this.running) {
         clearTimeout(this.running);
-        this.running = setTimeout(this._worker, 50);
+        this.running = setTimeout(this._worker, 200);
     }
 };
 
diff --git a/src/CursorLayer.js b/src/CursorLayer.js
index dcf4c2a7..b47f6af4 100644
--- a/src/CursorLayer.js
+++ b/src/CursorLayer.js
@@ -32,7 +32,16 @@ ace.CursorLayer.prototype.showCursor = function() {
 
     var cursor = this.cursor;
     cursor.style.visibility = "visible";
+    this.restartTimer();
+};
 
+ace.CursorLayer.prototype.restartTimer = function() {
+    clearInterval(this.blinkId);
+    if (!this.isVisible) {
+        return;
+    }
+
+    var cursor = this.cursor;
     this.blinkId = setInterval(function() {
         cursor.style.visibility = "hidden";
         setTimeout(function() {
@@ -68,4 +77,5 @@ ace.CursorLayer.prototype.update = function(config) {
     if (this.isVisible) {
         this.element.appendChild(this.cursor);
     }
+    this.restartTimer();
 };
\ No newline at end of file
diff --git a/src/Editor.js b/src/Editor.js
index 496375c3..70b4ee10 100644
--- a/src/Editor.js
+++ b/src/Editor.js
@@ -130,7 +130,7 @@ ace.Editor.prototype.onBlur = function() {
 ace.Editor.prototype.onDocumentChange = function(e) {
     var data = e.data;
     this.bgTokenizer.start(data.firstRow);
-    this.renderer.updateLines(data.firstRow, data.endRow);
+    this.renderer.updateLines(data.firstRow, data.lastRow);
 };
 
 ace.Editor.prototype.onTokenizerUpdate = function(e) {
diff --git a/src/VirtualRenderer.js b/src/VirtualRenderer.js
index 0c421b1c..8c92c961 100644
--- a/src/VirtualRenderer.js
+++ b/src/VirtualRenderer.js
@@ -77,8 +77,8 @@ ace.VirtualRenderer.prototype.onResize = function()
 ace.VirtualRenderer.prototype.updateLines = function(firstRow, lastRow) {
     var layerConfig = this.layerConfig;
 
-    // if the first row is below the viewport -> ignore it
     if (firstRow > layerConfig.lastRow + 1) { return; }
+    if (lastRow < layerConfig.firstRow) { return; }
 
     // if the last row is unknow -> redraw everything
     if (lastRow === undefined) {