Forum Discussion
Power Query load from Dataflow is excruciatingly slow
Try clearing the cache in Power BI Desktop.
If that doesn't help, is this on a laptop? Go to Starbucks or someplace else and see if the internet there is better. if that works, there could be a routing issue from your location that is causing a problem, or some other corporate firewall.
Also, you don't have to wait for the preview to finish to load. Just close Power Query and tell it to save (and apply) the data. Even if it fails the first time, hitting Refresh in Power BI desktop usually clears that up.Edit: oh, what dataflow connector are you using? Does the Source line say PowerPlatform.DataFlow or PowerBI.dataflow? Whatever it says, switch it out. I personally prefer the PowerBI.Dataflow as for raw speed it is faster, but doesn't allow folding or setting incremental refresh with it.
Recapping what I did and where it got me:
Yesterday I tried to allow it to refresh during the business day.
I started with trying to do a data refresh on the Power BI side and allowed it to run for ~ 2 hours and it did not complete. This was no substantial changes to the original model when I posted my original question.
I was running out of time in the day at this point.
Because I've seen previously where 'cancelling and trying again' has produced a successful refresh, I retried again and allowed it to run for about 45 minutes without completing.
I cancelled again and this time cleared the data cache as suggested by edhans. Looking back at this I may not have cleared the right cache.
I tried another refresh but could only give it about 20 minutes before I needed to leave. Still didn't have a successful refresh.
Last night and this morning I repointed all the dataflows to the PowerBI dataflow connector instead of the Power Platform Dataflows connector and retried.
I was able to get a full Power BI refresh in about 6 minutes.
A side note that during this refresh I did see my network download traffic get significantly higher (100 Mbps+ at some points) and my CPU was "working harder" than it had ever been when I originally posted this question. It seemed like Power BI was actually doing something.
Still going to keep an eye on this to see if something resurfaces, but this experience is not giving me confidence in the Power Platform Dataflow connector.
-- edit
The day after I posted this initially, I was in the office and was back to horribly slow refresh times even with the PowerBI dataflow connector.
I spent more time on this and tracked it down to a traffic shapping rule on the firewall which was limiting my bandwith to 512 KBps (~4Mbps) after changing this my refresh time went from ~1hr 20 to ~23 minutes and the "during refresh" experience on my computer was much better.
Hoping this will help someone else.