Forum Discussion

Zhinee's avatar
Zhinee
Helper III
1 year ago

How to Reproduce First-Time Loading Slowness in Power BI (Live Connection)?

I'm trying to reproduce the "first-time loading slowness" issue in a Power BI report that uses a live connection (to Power BI dataset). The slowness usually happens if I haven't used the report in 30 to 60 minutes—the first visual takes several seconds to load, but after that, everything runs smoothly.

I'm currently making some changes to the DAX query to see if there's any performance improvement, but I'm having a hard time reproducing the slowness consistently. I don't want to keep waiting 30–60 minutes every time just to test a small tweak.

Any advice or technical explanation on how this works behind the scenes—and how to trigger it—would be super helpful!

Need Help

5 Replies

  • johnbasha33's avatar
    johnbasha33
    Super User
    1 year ago

    Hi  

    1. Dataset Eviction / Idle Timeout

    Power BI datasets in the service go idle after 60 minutes (sometimes as low as 20–30 min depending on resource load). When a dataset goes idle:

    • The in-memory model is paged out to conserve resources.

    • The next query wakes it up, causing a cold start.

    • Cold start includes rehydrating metadata, restoring memory context, and priming caches.

      2. Query Plan Recompilation

      On the first access, some DAX queries might:

      Trigger query plan caching

      Force VertiPaq engine to reload dictionaries or precompute expressions.

      How to Reproduce Cold Start Slowness Faster

      🔁 Option 1: Use REST API to Refresh Dataset Memory

      Use the Power BI Admin REST API to:

      • Clear memory cache or simulate inactivity.
        Unfortunately, Power BI doesn't offer a direct unload dataset API, but...

        🧊 Option 2: Use Multiple Tenants or Incognito

        Try accessing the report from:

        • Incognito mode or a browser profile not used for 30+ min.

        • Different user accounts or new Power BI Desktop sessions.

          🧨 Option 3: Restart or Rotate Workspace Capacity

          If you're on Premium Capacity, go to the Admin Portal → Capacity Settings:

          • Restart the capacity to flush everything.

          • Or, assign the dataset to a new capacity.

            🔁 Option 4: Use a Proxy or VPN

            Session affinity and caching might be tied to location/IP. Try:

            • Switching VPN endpoints.

              Using a proxy to simulate a "new user" behavior.

              Did I answer your question? Mark my post as a solution! Appreciate your Kudos !!

    Zhinee

  • lbendlin's avatar
    lbendlin
    Super User
    1 year ago

    Make sure that the query cache option is disabled for the semantic model too.

  • v-karpurapud's avatar
    v-karpurapud
    Community Support
    1 year ago

    Hi Zhinee 

     

    Thank you for submitting your question to the Microsoft Fabric Community Forum, and thanks to johnbasha33 and lbendlin  for offering helpful suggestions.

     

    Could you let us know if the suggested solution resolved your issue? This information can assist other community members facing similar challenges.

    Thank you.

    • Zhinee's avatar
      Zhinee
      Helper III
      1 year ago

      Hello,

      The suggested solution does not resolve the issue. 
      Can you delete this post?

      • v-karpurapud's avatar
        v-karpurapud
        Community Support
        1 year ago

        Hi Zhinee 

        Thank you for the update. If you have found a solution or workaround, please share it here to assist other community members facing the same issue.

        Based on your last response, we will close this thread since the suggested solution did not resolve the problem. If you need further assistance, you are welcome to submit a new support request, and we will be happy to help.

        Regards,
        Karpurapu D,
        Microsoft Fabric Community Support Team.