At least this is what I do.
Probably not. Almost anything within vSphere is nothing but an API call, so vCenter should be able to answer to just some info queries very easily. This is what it’s made for. And due to the very slow VSAN API (which is different from vSphere API) the special agent is caching itself and will start a query every 15mins only (if left on defaults) which reduces overhead even more.
Regards,
ttr