Slow reports in Power BI Service

Hi, our organisation has just started using a premium capacity on the Power BI Service to host our reports and create apps and whilst the main front end of the service in the browser is responsive it is a different story when reports / apps are opened.

Upon opening an app or report the visuals can take upto 40-50 seconds to show any data which is obviously not the performance that we were expecting. We have checked through all of the usual supects, we have no extraneous date tables, the model is not overly complex and the model size is around 230mb.

Our dataset for the report is hosted in the service and when designing reports on a local desktop performance is snappy and as expected, the issue only occurs on the service when accessing reports via a browser (Microsoft Edge). Conversely I happend to have the Power BI client application installed and accessing the service via that is performant. The only difference that I can see is that via a browser our organisation forces us through a proxy server.

Looking at the developer console in Edge shows the following errors occuring:

PBI Service Errors displayed in Edge Developer Console

 Has anyone experienced anything similar? If so how was it solved, was it as simple as adding an exception rule to the proxy server or did it require more in depth confiuration changes?

Thanks, Chris