queryPerf and random timeout

Hi all, could you give me some advices on how to understand the root cause of this problem?


Code is performing q queryPerf call on realtime data. Every call is getting counters for Host and associated VMs. 


Randomly, call fails returning no data all. If I try to perform the same call some seconds after, I obtain no data. Usually, after 15/20min, call start working again.


Network is fine, I suspect a lack of resources on vCenter or a problem on host (an utilization spike?).


What should I have to look at in order to get the root cause of the problem?


 Thanks!