There is no practical limit on requests per minute for either the Premium or Standard APIs with the exception of the Flight Status Feed and the Connections API. In general, you can query the APIs thousands of times per minute and the response is in milliseconds.
However, the Flight Status Feed is throttled to 3000 requests per minute per user account as a safeguard against runaway processes that could slow down the entire system. To reduce the chance of hitting the rate limiter, your software will need to sleep 10 seconds if you see an empty /next operation.
With our Connections API, requesting complex routes may take 10 seconds for complex search to return the results. If you need to discuss enterprise use cases beyond this, we would refer you to your Cirium account manager.