Dynamics 365 includes a diagnostic tool for analysing connectivity and producing a report on the primary characteristics that affect the performance of Dynamics 365 instances. These characteristics include Latency, Bandwidth, and JavaScript performance.
You can execute the Dynamics 365 Diagnostics test on your instance by navigating to this URL https://.crm.dynamics.com/tools/diagnostics/diag.aspx, and clicking the Run button. The results of the test display in a text box and there is an option to send the results via email.

The Latency Test row value provides information on the average time a signal takes to travel from one point on a network to another across twenty individual test runs. Latency is a fixed cost between two points, and lower latency values provide greater performance for users connecting to a Dynamics 365 instance.

Bandwidth is the maximum rate of data transfer across a given path. Bandwidth and Latency are independent in that networks with high bandwidth do not guarantee low latency, and low latency values do not guarantee high bandwidth. The Bandwidth test calculates time, blob size, and speed across ten runs, and returns a maximum download speed value.

The results report also displays Array Manipulation, Morph, and Base 64 benchmark test results alongside browser, machine, and organization information.