Performance fluctuations RRS feed

  • Question

  • Hi all,

    I was wondering what would be the reason (and how to monitor/avert that) for a PQ query refresh performance to fluctuate considerably?

    I've got a reasonably complicated (I'd think) PQueries pulling/combining data from multiple (16) xl files. The point is that the same query at some point refreshes within 33seconds, at some other point 90 seconds. And nothing (as far as I can tell) has changed between the two refreshes - the same files with the same data, the same PQuery. All files on my Laptop, no i-net, nor LAN implications. Just sometimes the refresh is real quick but sometimes real slow (Allow data preview to download in the background = disabled).

    It would seem (not 100% certain though) that it affects all PQueries - also in other files (not just this one) which would make me think that it's to do with my Laptop rather than the file/s... But how would I check/verify and hopefully fix that - to make the PQs quick every time?

    I'm on 64bit W10 Home, 64bit Excel2019. 8Gb RAM

    Any clues?

    Thursday, May 16, 2019 10:19 AM


  • If you feel comfortable sharing traces, please collect two traces, one with bad performance and one with good performance.

    1. Enable Tracing

     (In Power BI desktop,  go to menu item File -> Options and Settings -> Options, then under Global settings choose Diagnostics, and Enable Tracing )

    While you're still in the Options and Setting dialog go to Diagnostics and click on Open crash dump / traces folder. Ensure the folder is clear before capturing new traces.

    1. Reproduce the issue.
    2. Once done, close Power BI, so the logs are flushed to disk.
    3. Repeat again for different performance characteristics. (May take a few times if it is not consistently slow and consistently fast). Perhaps capture a few and just share the quickest and the slowest. Make sure traces are kept separate.

    Monday, May 20, 2019 9:28 PM