CRM Diagnostics Page to Capture Network Performance:
To use the diagnostics page you can simply browse to the page by using the URL http://<YourCRMServerURL>/tools/diagnostics/diag.aspx and click the Run button to start the tests. This page is available for both CRM Online and OnPremise
This CRM Diagnostics page will issue a series of pings from client to server and transfer several blobs of data. Based on this data it will provide the latency in milliseconds and max transfer speeds achieved. This is a quick and easy way to identify the network performance without having to install any tools on the client or server.
In the Optimizing and Maintaining Client Performance for Microsoft Dynamics CRM 2011 and CRM Online document it states that “Microsoft Dynamics CRM is designed to work best over networks with latency under 150 milliseconds”.