title: Azure functions are slow
body: <p>I’m testing the CPU performance of functions, so I made a function that finds the prime numbers in a number. It is triggered by Azure Service Bus.
  On my local machine it runs in 350ms.</p>
  
  <p>The function, when running in a consumption plan, takes around 1000ms.
  When I batch send 100 messages to the function, it does scale up to around 16 instances, but the performance of each function decreases considerably to between 3000-7000ms.</p>
  
  <p>When trying a standard service plan with 4 cores, the performance is better, but not that much. It is still considerably slower than my laptop.
  This guy here has a <a href="https://www.youtube.com/watch?v=n9qpQREYyIA" rel="noreferrer">similar issue</a>.</p>
  
  <p>Is this the performance/scaling to be expected from functions? E.q. not a great fit for batch processing of CPU intensive methods?</p>
  
  <p>Would Azure batch be a better fit?</p>