Run the Time Detail Report to see down to the minute reports.  We can’t report on CPU and Memory info down to the minute, but you can see the session starts.  You can also run the Concurrent User Report to see down to the minute info on peak usage, unique users and session starts – but this report takes much longer to run than the Time Detail due to the number crunching that goes on for concurrent usage in the OLAP db.   But if you don’t need concurrency and just need sessions by server, app or user, then use Time Detail.  Plus you can see Unique User count by the sum of the users listed (if you include the User level).

If you run concurrency report, run it for a small time period to start - maybe one day and see how long it takes. If it takes more than an hour, then go ahead and create the report for a longer time period, like one month, but run it on a schedule in batch mode.