Why Is Azure OpenAI API Response Slower Than the Assistant Playground?

Question

Hi everyone, I’ve been testing Azure OpenAI using both the Assistants Playground in Azure AI Studio and the API directly, and I’ve noticed a big difference in response speed.

The Playground returns results in just a few seconds, but when calling the same assistant via the API, the response takes much longer sometimes over a minute.

Is there any known reason for this delay when using the API? Any way to optimize or speed it up?

Answer 1

Hi there arsh arsh

Thanks for using QandA platform

The Assistants Playground in Azure AI Studio benefits from streaming responses and optimized backend handling, which makes it feel much faster.

When using the API directly, if you’re not using streaming, the full response is generated before it’s returned — which causes that delay. To improve speed: Enable streaming in your API call (you’ll get tokens as they’re generated). Make sure your tooling and network latency aren’t adding overhead. Try smaller max_tokens, or simplify system messages for quicker responses.

If this helps kindly accept the answr thanks much.

Answer 2

There are a factors to take into account:

1. Streaming vs non-streaming responses:
   • The Playground typically uses streaming responses, meaning tokens are sent back as they are generated.
   • If you're calling the API without enabling streaming (stream: true), it waits to generate the entire response before returning anything — which makes it feel slower.
2. Cached context:
   • In some Playground sessions, context is cached or kept warm, especially for short repeated prompts. When you call the API directly, each call might be creating a cold start or dealing with a longer input context.
3. Thread & tool overhead:
   • If you're using the Assistants API, response time can be affected by tool calls (code interpreter, function calling, retrieval, etc.). Even when no tool is explicitly invoked, the system may still process and evaluate potential tool use.
4. System message and prompt length:
   • Longer system messages or thread history increases token processing time. The Playground might minimize this behind the scenes for repeated messages.

To optimize API response time, consider the following

1. Enable streaming:
   • Set stream: true in your API request. This starts sending tokens as soon as they’re available.

      {
        "stream": true
      }
   

   • With streaming, you typically get the first tokens within 1-3 seconds, even for longer responses.
2. Minimize input tokens:
   • Keep your thread history short. Only include essential context in each message.
   • Avoid sending repeated system instructions unless necessary.
3. Assistant tools:
   • If you're not using any tools, explicitly disable them in the assistant definition to reduce overhead.
   • Tools can cause background work even if they aren’t used in a particular response.
4. Use high-performance SKUs:
   • Check which Azure OpenAI model SKU you're using (e.g., gpt-4, gpt-4-turbo, gpt-35-turbo). gpt-4-turbo is typically much faster and cheaper than gpt-4.
5. Reduce function call usage:
   • If your assistant definition includes a lot of functions, or even retrieval functions, consider if you can streamline that — especially if the assistant often evaluates all of them.

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hth

Marcin