periodInSeconds
The granularity, in seconds, of the data points returned from Performance Insights. A period can be as short as one second, or as long as one day (86400 seconds). Valid values are:
1(one second)60(one minute)300(five minutes)3600(one hour)86400(twenty-four hours)
If you don't specify PeriodInSeconds, then Performance Insights will choose a value for you, with a goal of returning roughly 100-200 data points in the response.