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

[Zhinee]

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!

[v-karpurapud]

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]

Hello,

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

[v-karpurapud]

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.

[lbendlin]

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

[johnbasha33]

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