The queries are only run when you or a member of your team is using the service. If no one on your team is using Chartio, Chartio will not query your server.
The results are also cached locally in your browser for 5 minutes to avoid excessive querying as you flip through your charts and dashboards. If you leave the page open in your browser or on a TV, the queries will be run to automatically keep the data fresh, every 10 minutes by default.
For more information about caching, please see our Knowledge Base article.