This help article describes how to improve the performance of your ASP.NET application by disabling the RadCaptcha audio handler.
RadCaptcha provides the functionality to request audio for the capthca rendered. You can read more about it in the Using Audio Code article.
This feature is available by using a built-in handler for the audio. Which is available with disabled Audio Code feature and also without using RadCaptcha on the page.
CaptchaDenyAudioHandler key to
true in the web.config file.
<add key="Telerik.Web.CaptchaDenyAudioHandler" value="true"/>