Hi,
There's no other way to calculate the summary response/request time. You can do this just as you described: go through each connection and sum up the time spent to simulate all the requests that were made through the connection and the time spent to receive the responses.
As you have noticed, the task execution time (the value displayed in the
Time(s) column of the Users panel) is not equal to the sum of request execution time. This difference is caused by the specifics of time measurements in TestComplete, as well as by helper operations performed when simulating traffic.
When you calculate the request execution summary time, the resulting value is the true time spent on executing requests. This time is one of the components the task execution time consists of. Besides that, the total execution time contains load testing engine initialization time, connection initialization and finalization time and time needed to log results. That is why, the lifetime of virtual users (in your case, 66 seconds) is much more than the summary request/response time (in your case, 10 seconds).
For more information on this, see the
HTTP Load Testing - Timing Task Execution help topic.