C# – First call to a .net webservice is slow

.net-4.0asmxcvb.netweb services

I'm calling a .net webservice from my .net winforms app, both in framework 4.0. During the execution of the program, the first time the webservice has a method called, the call takes ~10-12 seconds. Subsequent calls take ~1-2 seconds. Subsequent calls, even when the web reference instance is recreated, are still ~1-2 seconds. When the winforms app is restarted, the first call delay occurs again, but subsequent calls are responsive.

The instance of the web reference is being created prior to the call occuring, and is not part of the delay.

XmlSerializers for the winforms app are being generated (and used, as far as I know, but I'm not sure how to verify this).

The delay is not occuring because of a first-run compilation on the webservice side. This is a production webservice that is being used throughout the day, and its apppool is remaining in memory. As far as I can see, the delay is occurring either on the client side, or between the client and the server for that first call, but not subsequent calls.

Not sure what to check next. Any ideas?

Best Answer

As spender had indicated, the issue had to do with the proxy detection. Turning that off in Internet Explorer solved the problem, but was not feasible to do in my situation.

Instead, there is a workaround to bypass the use of the default proxy, and therefore the automatic detection.

Adding these entries to the app.config allows certain URLs to bypass the proxy:

<configuration>
    <system.net>
        <defaultProxy>
            <bypasslist>
                <add address="server/domain name" />
            </bypasslist>
        </defaultProxy>
    </system.net>
</configuration>

More information can be found here: <defaultProxy Element> on MSDN

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