At the top of the device detail page, you might see a warning like this one:
Warning! The Collector Frequency might be too aggressive. We recommend you increase the Collector Frequency to 3 minutes. (44 out of 150 device pollings took over 75% of the Collector Frequency)
This happens when at least one device polling has taken more than 75% of the Collector Frequency during the time range selected on the page. If it happens only once in a while and there are no holes in the graphs, you can ignore this message. However, if it happens often and you start seeing holes in the graph like the one below, we recommend you increase the Collector Frequency setting for that device.
Why are only some devices affected?
We usually see this with devices with a high number of interfaces (such as a stack of switches) and a CPU with low-resources for management tasks such as SNMP. It can also be caused by a too aggressive control-plane policing or rate-limiting which can sometimes be configured to allow more traffic in order to have a faster collection.