http://blogs.msdn.com/junfeng/archive/2007/07/09/reverse-p-invoke-marshaling-performance.aspxPlatform Invoke allows managed code to call unmanaged functions exported by an DLL. While the reverse P/Invoke allows managed code to pass a managed delegate as a callback to native code. Both P/Invoke and Reverse P/Invoke requires parameter marshalingen-USCommunityServer 2.1 SP1 (Build: 61025.2)http://blogs.msdn.com/junfeng/archive/2007/07/09/reverse-p-invoke-marshaling-performance.aspx#3784337Mon, 09 Jul 2007 21:16:44 GMT91d46819-8472-40ad-a661-2c78acb4018c:3784337DevDuck<p>Can you explain why there is such a large difference?</p> http://blogs.msdn.com/junfeng/archive/2007/07/09/reverse-p-invoke-marshaling-performance.aspx#3798878Tue, 10 Jul 2007 17:04:17 GMT91d46819-8472-40ad-a661-2c78acb4018c:3798878Carlos<p>Yeah, I wondered that.</p> <p>So I fired up .Net Reflector. &nbsp;Marshal.PtrToStringUni allocates a StringBuilder, copies in the new string data, then allocates a new string from the StringBuilder. &nbsp;In other words, it seems to be doing twice as much work as necessary. &nbsp;(The further overhead may be extra GC work, but I'm speculating.)</p> <p>This should probably be filed as a performance bug.</p>