Question:

<strong>The scenario</strong>

I have an ASP.NET website that works perfectly in Internet explorer 8, but is extremely slow in Internet Explorer 10.

<strong>The Problem</strong>

In Internet Explorer 8 a postback or button click event takes about 1,5 seconds to complete. In internet explorer 10 it takes a minimum of 30 seconds and sometimes over 60 seconds.

<strong>What I already tried</strong>

1.Installed a hotfix from Microsoft's website to update the browser definition files (<a href="http://support.microsoft.com/kb/2836939" rel="nofollow">http://support.microsoft.com/kb/2836939</a>)

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I tried forcing IE8 and IE9 Compatibility Mode in web.config or adding HTTP Header in IIS or directly inside html pages.

</li> <li>

Tried changing the application pool in ISS on the server(Windows server 2008 R2).

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Installing .NET framework 4.0 on client machine

</li> </ol>

<strong>The Real question</strong>

Could ASP.NET still be having issues detecting Internet Explorer 10 as a browser, or could the slow response time between the browsers be a problem on the web server(browser definition files etc.)?

When using Internet Explorer to browse a page that contains an UpdatePanel, there is a delay (often anywhere between 10 seconds and 45 seconds or more) after clicking a page element that initiates an async postback. The delay is not experienced when using browsers other than Internet Explorer.

The PageRequestManager's _destroyTree method iterates through the DOM elements inside of the UpdatePanel prior to initiating an async postback in order to dispose of DOM elements. The _destroyTree method's specific implementation is very slow in Internet Explorer when working with a large DOM tree under some conditions due to the way that Internet Explorer's HTML viewer (mshtml.dll) stores DOM elements in memory.

Add the JavaScript below immediately before the closing </body> element of the page experiencing the delay.

<script language="javascript" type="text/javascript"> function disposeTree(sender, args) { var elements = args.get_panelsUpdating(); for (var i = elements.length - 1; i >= 0; i--) { var element = elements[i]; var allnodes = element.getElementsByTagName('*'), length = allnodes.length; var nodes = new Array(length) for (var k = 0; k < length; k++) { nodes[k] = allnodes[k]; } for (var j = 0, l = nodes.length; j < l; j++) { var node = nodes[j]; if (node.nodeType === 1) { if (node.dispose && typeof (node.dispose) === "function") { node.dispose(); } else if (node.control && typeof (node.control.dispose) === "function") { node.control.dispose(); } var behaviors = node._behaviors; if (behaviors) { behaviors = Array.apply(null, behaviors); for (var k = behaviors.length - 1; k >= 0; k--) { behaviors[k].dispose(); } } } } element.innerHTML = ""; } } Sys.WebForms.PageRequestManager.getInstance().add_pageLoading(disposeTree); </script>