Thank you for your patience.
Based on your example, you want to calculate the time after the user clicks on the Left Menu, to the time the entire page is loaded.
If this is correct, your calculation will begin from the first click to the time the last element is loaded. This is includes all the js., Css., Aspx pages, images, ascx controls etc. According to your example, a result based on step 2 will provide you with the closest representation of that time.
Our documentation provides an equation on how to Calculate Total Step Time:
Total Step Time = (Time that the Step Ended Execution + Time for the Next Step's Element to be Located) − Time that the Step Started Execution.
If you have any other questions regarding Test Studio's Performance Testing, please let me know. Unfortunately, I won't be able to address any more questions regarding the comparison between our software and HTTPwatch. We have the tools to research and assist with with our software's features but we cannot offer the same level of support regarding HTTPWatch. Being someone elses tool, we have no idea how it performs its measurements.
I hope this information helps.
the Telerik team