Always set your device cache-timeout setting to 60 seconds

The cache-timeout setting on your device specifies the length of time for which the list of NetFlow top talkers (unaggregated top flows) is retained. It specifies the active flow timeout in seconds that is in range 1 - 604800 (7 days). By default, it is 30 minutes.

Set the device configuration for NetFlow active timeout as follows:
Router(config)# ip flow-cache timeout active 1

With this cache-timeout setting, you specify the device to export flow records every minute to get the real-time traffic reports. Network Performance Insight® calculates utilization based on the Flow records it receives at 1-minute intervals. If it is not set to 60 seconds, utilization might go over 100%.