1) These Health Check or Monitoring Graph (which reports on Memory / Disk Usage / Query cache / Indexes etc) reports in real time - So wondering if this causes extra load on AEM server repeatedly to gather data.
2) Also if it OK to run such reports at regular interval like every 4 hour on AEM Publisher in Production ?
If you are worried that your customers will experience a performance drop if you check the reports, the answer is... yes but no... 😂 Technically you are correct, the reports are updated in real-time so there will be an impact on the instance's performance, however:
The impact is negligible unless you have a HUGE amount of content
If you are using a Dispatcher (as you absolutely should!) then the customer will see no difference sine the content is largely being served from cache.
I'm not sure what you mean by "OK" but for the reasons I mentioned above, there should be little to no impact for running these reports 🙂