The Importance of Caching LLM Calls
Understand the economic and performance benefits of caching LLM responses and embedding lookups in production.
The Importance of Caching LLM Calls is a free LLM Apps in Production (RAG + Vector DB + Caching) lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the LLM Apps in Production (RAG + Vector DB + Caching) learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What is Caching?
Imagine you look up a word in a dictionary. If you need to look up the same word again, it's faster to remember it than to open the dictionary and find it again.
Caching is like remembering. It stores results of expensive operations so you can reuse them quickly instead of re-doing the work.
LLM Calls: Not Free
Large Language Models (LLMs) often charge per "token" used. Every time your application sends a prompt and receives a response, you pay for the tokens.
- Prompt tokens: The text you send to the LLM.
- Completion tokens: The text the LLM generates back.
Repeatedly asking the same question means repeatedly paying for the same work.
LLM Calls: Can Be Slow
Even if costs weren't an issue, calling an external LLM API takes time. This is called latency.
Network requests, model inference time, and API response processing all contribute to delays. For interactive applications, users expect fast responses.
Introducing Caching for LLMs
This is where caching becomes a superpower for LLM applications! Instead of always calling the LLM, we can store its responses for common or identical requests.
When a user asks a question, your app first checks the cache. If the answer is there, great! If not, then it calls the LLM and stores the new response in the cache.
Caching Saves Money
The most direct benefit of caching is cost reduction. By serving cached responses, you avoid sending requests to the LLM API.
This means fewer tokens used, leading to lower bills from your LLM provider. For applications with many users asking similar questions, the savings can be substantial.
Caching Boosts Speed
Retrieving data from a local cache is significantly faster than making an external network call to an LLM API. We're talking milliseconds versus seconds!
Faster responses lead to a much better user experience. Your application feels snappier and more responsive, which is crucial for engagement.
Caching Embeddings Too
It's not just LLM responses that benefit from caching! Generating vector embeddings also involves an API call (or local computation) and costs money/time.
If you're frequently embedding the same chunks of text (e.g., user queries or document chunks for retrieval), caching these embeddings can also save costs and speed up your RAG pipeline.
Smart Caching Decisions
Caching is most effective for LLM calls that are:
- Deterministic: The LLM always gives the same (or very similar) answer for the same prompt.
- Frequent: The same prompt is likely to be asked multiple times.
- Static: The underlying information doesn't change often.
Avoid caching for highly dynamic or personalized responses that change with every request.
Caching in Action (Python)
Here's a simplified Python example showing the logic of a basic cache for LLM calls. It checks if a prompt is already in our cache dictionary.
llm_cache = {}
def call_llm_api(prompt):
# Simulate a slow, costly LLM call
import time
time.sleep(0.1) # Short delay for demo
return f"LLM response for: '{prompt}'"
def get_llm_response(prompt):
if prompt in llm_cache:
print("Cache hit!")
return llm_cache[prompt]
else:
print("Cache miss! Calling LLM...")
response = call_llm_api(prompt)
llm_cache[prompt] = response
return response
if __name__ == "__main__":
print(get_llm_response("What is RAG?"))
print(get_llm_response("What is RAG?")) # This should be a cache hit!
print(get_llm_response("Explain caching."))Benefits of Caching
Based on what we've learned, what are the primary benefits of implementing caching for LLM API calls?
Recap: Why Caching Matters
In this lesson, we explored the critical reasons for implementing caching in LLM applications. We learned that caching helps:
- Reduce costs: By minimizing redundant LLM API calls.
- Improve performance: By drastically lowering response times for frequent queries.
- Optimize embedding generation: Extending benefits beyond just LLM responses.
Next, we'll dive into different strategies for implementing these caches.
Frequently asked questions
Is the “The Importance of Caching LLM Calls” lesson free?
Yes — the full text of “The Importance of Caching LLM Calls” is free to read here on the web, and the LLM Apps in Production (RAG + Vector DB + Caching) course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the LLM Apps in Production (RAG + Vector DB + Caching) course, upgrade to CoddyKit PRO.
What will I learn in “The Importance of Caching LLM Calls”?
Understand the economic and performance benefits of caching LLM responses and embedding lookups in production. You practise LLM Apps in Production (RAG + Vector DB + Caching) with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start LLM Apps in Production (RAG + Vector DB + Caching)?
No prior experience is required. LLM Apps in Production (RAG + Vector DB + Caching) on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “The Importance of Caching LLM Calls” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this LLM Apps in Production (RAG + Vector DB + Caching) lesson?
Yes. Every LLM Apps in Production (RAG + Vector DB + Caching) lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- The Importance of Caching LLM Calls
- In-Memory and External Caching Strategies
- Integrating Caching into a RAG Pipeline
- Semantic Caching for LLM Apps