ASP.net session request queuing

Solution 1:

This behaviour is by design; no concurrent access to the session state is allowed. Requests with same SessionID will be locked exclusively to prevent potential corruption of its state.

To get around this you can disable session state in your page directive.

<%@ Page EnableSessionState="false" %>

Read "Concurrent Requests and Session State" here http://msdn.microsoft.com/en-us/library/ms178581.aspx for more.

Setting EnableSessionState="ReadOnly" will prevent that page from gaining an exclusive lock on the SessionState (but the page itself would have to wait for other non-ReadOnly requests by the user to finish before loading).

(This is a copy and paste of my answer to this question ASP.net site: Long-loading page for user puts all other page loads for user on Hold)