Over the years I’ve seen a few examples of how issues with an organisation’s corporate network can affect Power BI report performance. I’ve never blogged about them because, to be honest, I know next to nothing about networks and I’m not sure I could describe them properly. However, recently, I have seen a few instances of what I think could be a widespread but little-diagnosed problem – so I would like you to check if it’s happening to you and tell me what the cause is, if you can find out.
Some time ago I wrote a post about how Power BI report performance could be worse in Internet Explorer 11 and older Windows operating systems because some report performance optimisations we do are only available with HTTP/2. You can read it here:
I hope you’re not still on Windows 8.1 or using IE11. Some traffic could still be being forced to use HTTP/1.1 though and this could have a big impact on report performance – in some cases making reports 5-10 seconds slower to render. How can you tell? You will need to use the Developer Tools available in Chrome and Edge. I blogged about how to use the Network tab in Developer Tools to measure Power BI report performance here:
You will also need to make sure the Protocol column is visible by right-clicking in the central pane where the traffic is displayed:
Here’s an example of what you’ll see in the Network tab when the report renders and you have the problem:
There are two things to look out for:
- In the Protocol column you’ll see the value “http/1.1” rather than “h2” for some events, most importantly the query events
- You’ll see a long grey bar before the green bar in the Waterfall diagram for these events showing that the connection is stalled for several seconds
If possible you should compare the performance of running your report inside your corporate network and outside it, using the technique described in the blog post mentioned above to see how long the report takes to render in both cases. If the report is faster outside your corporate network, and you only see traffic being forced to use http/1.1 and connections stalled inside your corporate network, then you have a problem and need to talk to your networking team to find out what’s going on. I’ve heard ZScaler could be the culprit but I’m not sure, so if you do have this problem and do find out the cause and the solution, please leave a comment below.