The ability to enable / disable the Undo / Redo feature of RadEditor is still not offered by the editor control. Its implementation was postponed for indefinite time due to features logged with high priority. You can find all features and bug fixes integrated in the latest editor versions in the Release History
I logged your request in our new Public Issue Tracking system, which will become available for public usage on our site this week, and you and your fellow developers will be able to vote and increase the priority of this feature.
The information below could be helpful for your scenario:
There are five main reasons responsible for the slow editor performance when editing large XHTML/HTML files (>100KB).
Reason 1: The undo/redo mechanism and other maintenance code that ensures the smooth user experience - it gets increasingly cumbersome and time consuming for the browser to execute it if huge content is in the editor.
Reason 3: test the performance only when <compilation debug="false"
in your web.config. When it is true, the MS AJAX debugging code kicks in and causes a severe performance hit on the client-side.
Reason 4: Remove the RadEditor modules, e.g.
<telerik:radeditor runat="server" ID="RadEditor1">
<telerik:EditorModule Visible="false" />
Reason 5 (valid when switching between the view modes or submitting the content): In difference with the TextBox control which does not process the content when submitting it to the server, the RadEditor runs content filters which validate the non well formatted content and make it XHTML compliant. Right now the editor runs more than 11 content filters. These filters run regular expressions which parse and validate the large content, which slow down the content submission to the server. You can disable the filters by setting ContentFilters
property to None
<telerik:RadEditor ID="RadEditor1" ContentFilters="None" runat="server"></telerik:RadEditor>
Being cross-browser is a top priority, and thus at present it rules out changing the editor's technology.
We are constantly working on improving the speed, but the browsers do have their limits, and it is not hard to reach them when editing large content in the editor.
You can find more information in the following KB article: RadEditor loads slowly (high CPU utilization)
We strongly suggest avoiding loading, pasting or saving more than 100KB of content into the editor in a real-world scenario (that is, other than for test purposes) - as an actual user will not get a good experience if they have to deal with editing 100KB of HTML on a single go.
the Telerik team