Charts load times are way longer than reported in the Duration column in the App Script Executions

Description of the problem

We are Automatichat, a Chat Marketing agency. We have created a Community Connectors for Looker Studio. We are currently experiencing an issue that we believe is related to Looker Studio. Sometimes the load times of the graphs in a report are much longer than the time reported in the App Script run logs. We are trying to understand if this is a problem with Looker Studio or if it is a problem with our connector. On our end, each getData run is marked as Completed with the correct result in, say, 5 seconds, but the graph takes up to 1 minute or more to load. Sometimes it fails to load and a system error appears.