AI GLOSSARY
Latency
Latency is the time between a request to an AI system and the response. It determines user experience, scalability, and costs. Those who ignore latency build applications that perform well in the lab but fail in real-world use.
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Time Ranges
Sub-second, seconds, minutes
Influencing Factors
Model, Context, Infrastructure, Network
Approaches
Streaming, caching, smaller models
Best Practices
for Low Latency
Why Latency Is Critical for AI Applications
Users give AI applications just a few seconds. Anything that takes longer loses their attention and acceptance. Latency is therefore not a peripheral issue—it is a key success factor for every productive AI application.
User Acceptance
Response times longer than 5 seconds are perceived as too slow. Adoption plummets.
Competitive Advantage
Faster applications attract users—latency is a key differentiator.
Scaling Limit
High latency limits the number of concurrent users—the infrastructure must grow disproportionately.
Cost Factor
Latency optimization often reduces costs as well—faster models are usually more cost-effective.
Business Processes
In real-time processes (fraud, trading), milliseconds are critical.
SLA Commitments
B2B customers demand guaranteed response times—latency is becoming a contractual issue.
What is latency in AI?
Latency is the time between sending a request and receiving a response. In AI applications, it encompasses several components: network latency, model processing time, database access (in RAG), response generation, and transmission.
Typical time ranges: sub-second (classification, embeddings, text extraction), 1–5 seconds (standard LLM queries, RAG responses), 5–30 seconds (complex reasoning tasks, large contexts, AI agents using tools), minutes (batch processing, in-depth analysis workflows).
Factors affecting performance: model size (smaller models respond faster), context window (more input, longer processing time), infrastructure (GPU availability, proximity to the region), provider utilization (slower during peak times), network (faster on-premises than via the cloud across continents).
For small and medium-sized businesses, latency design is practically relevant: What response time does the user expect? What is the acceptable limit? The answers to these questions drive model selection, architecture, provider choice, and costs. Latency is therefore a business decision, not just a technical one.
Techniques for Latency Optimization
These eight techniques form the backbone of fast AI applications:
Streaming
Prompt Caching
Smaller models
Regional Deployment
Batching
Speculative Decoding
Query Optimization
Asynchronous Processing
Best Practices for Low Latency
These six principles have proven effective:
- Measure from the start: Track latency per component—not just total latency.
- Streaming-first: Always use streaming for interactive applications—perceived latency is cut in half.
- Choose the right model: Bigger isn’t always better—smaller is often faster and sufficient.
- Control prompt length: Shorter prompts are faster—every token costs time.
- Use caching: Cache recurring requests and prompt parts—this significantly speeds things up.
- Define an SLA: Set clear targets for p50, p95, and p99 latency—measurable and negotiable.
Range 1
Sub-second
Classification, embeddings. The user doesn't notice any delay. Standard for simple tasks.
Instant
Range 2
1–5 seconds
Standard LLM chat. Acceptable with streaming. Good for most applications.
Chat
Section 3
10+ seconds
Complex reasoning, agents using tools. Async UX or status display required.
Complex
Common Mistakes Related to Latency
We often see these pitfalls:
- No streaming: The user waits 10 seconds for a complete response—with streaming, they would see something immediately.
- Usingthe Largest Model Unnecessarily: GPT-4 for a task that GPT-4o-mini can handle—5 times slower.
- Unfiltered RAG: Too many chunks in the context—each request takes longer than necessary.
- Wrong region: Model in the U.S., user in Germany—network latency adds 100+ ms.
- No monitoring: Latency issues aren’t discovered until users complain—too late.
Time-to-First-Token vs. Total Latency vs. Throughput
Three key latency metrics:
- Time-to-First-Token (TTFT): Time until the first token is generated. Critical for the user experience during streaming.
- Total Latency: Total time until a complete response is received. Important for non-interactive processes.
- Throughput: The number of requests per second. Relevant for scalability.
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Frequently Asked Questions About Latency
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What level of latency is acceptable?
For interactive applications: less than 3 seconds (with streaming). For voice: less than 1 second. For batch: irrelevant.
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How do I measure latency correctly?
Don't just measure the average—measure the 95th and 99th percentiles as well. The bottom 5 percent often determine the user experience.
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Why is my AI chatbot slow?
Typically: large model, long prompt, extensive retrieval, no streaming. Measure and optimize systematically.
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What is Time-to-First-Token?
The time it takes to generate the first token. In streaming, this is what determines the user experience—not the total response time.
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Is on-premises faster than the cloud?
That might be true if users are nearby. But cloud providers often have better GPUs and higher utilization—on-premises isn't always faster.
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What is Speculative Decoding?
A small model quickly suggests several candidate tokens, while a large model verifies them in parallel. This speeds up generation by a factor of 2–3.
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How is latency related to cost?
There is usually a positive correlation—faster models are often less expensive. An important exception: heavy batching reduces costs but can increase latency.
Optimize the Latency of Your AI Applications
In a free initial consultation, we’ll analyze latency bottlenecks in your AI applications and outline an optimization plan—with clear target metrics.
As an AI partner for small and medium-sized businesses, we build fast AI applications with clean streaming architecture, appropriate models, and active monitoring.
What We Offer
- AI Consulting — Architecture and Latency Optimization.
- Inference in the Glossary — What Happens with Every Response.
- Inference Costs in the Glossary — Considering costs and latency together.
- AI Monitoring in the Glossary — Continuously monitor latency.