The rest endpoint service/statistic.json is called every 30secs by the Admin UI to update the service status badge on the statistics tab.
This call though can take over a sec to be resolved on a large deployment as it also gathers information about the jobs running on each service. This information is unnecessary to just update an icon to show how many services need sanitizing.
An administrator who has the admin UI open all day can and hour of database time just refreshing this icon and could be higher as it calls the endpoint each time the page is reload (eg clicking a tab).
The rest endpoint needs to be changed so that the service stats can be returned without the job information.