<p>About 5000 computers will be making a call to a central server, and they will be passing in a GUID to the central server.</p>

<p>The server will then return True/False back to the client.</p>

<p>Is there a big difference in <strong>performance</strong> between a web service and a regular Http request to a Url on the server?</p>

I am not 100% sure on a performance benefit in response time, but a WebService request that returns just the true false, rather than a regular http request and then parsing the response I'm guessing would be more efficient overall.