Too many outstanding request

I am accessing my Nginx logs with Loki and promtail and displaying them on Grafana.

When I am creating 3-4 panels for Status(like 200, 304 , 404 etc) then it is failing and not able to display the data quickly and getting the error : “too many outstanding query”

And in the production I have to deal with large dataset if it is not working now how can I use it for the production.