Groq and Cerebras: The Inference Speed Revolution Reshaping LLM Deployment

The Inference Bottleneck

Training LLMs gets most of the attention, but inference is where the money is. Once a model is trained, it serves millions of requests — and the speed of each request directly impacts user experience and cost. GPU-based inference has improved steadily with techniques like KV-cache optimization, speculative decoding, and quantization. But two companies are taking a fundamentally different approach: building custom silicon designed from the ground up for LLM inference.

Groq and Cerebras are challenging the assumption that GPUs are the best hardware for running LLMs in production.

Groq's Language Processing Unit (LPU)

Groq's LPU is a deterministic compute architecture — no caches, no branch prediction, no out-of-order execution. Every computation is scheduled at compile time, which eliminates the memory bandwidth bottlenecks that plague GPU inference.

flowchart LR
    REQ(["Request"])
    BATCH["Continuous batching<br/>vLLM scheduler"]
    PREF{"Prefill or<br/>decode?"}
    PRE["Prefill phase<br/>parallel attention"]
    DEC["Decode phase<br/>token by token"]
    KV[("Paged KV cache")]
    SAMP["Sampling<br/>top-p, temp"]
    STREAM["Stream tokens<br/>to client"]
    REQ --> BATCH --> PREF
    PREF -->|First token| PRE --> KV
    PREF -->|Next token| DEC
    KV --> DEC --> SAMP --> STREAM
    SAMP -->|EOS| DONE(["Response complete"])
    style BATCH fill:#4f46e5,stroke:#4338ca,color:#fff
    style KV fill:#ede9fe,stroke:#7c3aed,color:#1e1b4b
    style STREAM fill:#0ea5e9,stroke:#0369a1,color:#fff
    style DONE fill:#059669,stroke:#047857,color:#fff

Performance Numbers

As of early 2026, Groq's cloud API delivers:

• Llama 3.3 70B: ~1,200 tokens/second output speed
• Mixtral 8x7B: ~800 tokens/second
• Llama 3.1 8B: ~3,000+ tokens/second

For comparison, a well-optimized GPU deployment of Llama 3.3 70B typically achieves 80-150 tokens/second per user. Groq is delivering 8-15x faster inference.

Why Deterministic Execution Matters

The LPU's deterministic execution model means consistent latency — every request takes the same time for the same input length. There is no variance from cache misses or memory contention. For applications that need predictable performance (real-time voice agents, interactive coding assistants), this consistency is as valuable as the raw speed.

Current Limitations

Groq's inference speed comes with tradeoffs. The LPU architecture requires models to fit in on-chip SRAM, which limits the maximum model size. The largest models (400B+ parameters) do not run efficiently on current Groq hardware. Additionally, Groq's cloud capacity has been constrained — high demand frequently leads to rate limiting during peak hours.

Cerebras Inference with Wafer-Scale Chips

Cerebras takes an even more radical approach: a single chip the size of an entire silicon wafer (46,225 square millimeters compared to an A100's 826 square millimeters). The CS-3 chip contains 4 million cores and 44 GB of on-chip SRAM.

Architecture Advantages

The wafer-scale approach eliminates the inter-chip communication bottleneck that limits GPU clusters. When running LLM inference on multiple GPUs, data must be transferred between chips via NVLink or InfiniBand — this is often the bottleneck, not the compute itself. Cerebras' single-chip approach keeps everything on-die.

Cerebras Inference delivers:

• Llama 3.1 70B: ~2,100 tokens/second
• Llama 3.1 8B: ~4,500+ tokens/second

These numbers represent the fastest publicly available LLM inference speeds as of March 2026.

Cerebras' Cloud Strategy

Cerebras launched its inference cloud in 2025 and has steadily expanded capacity. The pricing model is competitive with GPU-based providers on a per-token basis, which means users get significantly faster responses at roughly the same cost.

What This Means for Application Architecture

Real-Time Conversational AI

At 1,000+ tokens per second, LLM responses arrive faster than a human can read. This enables truly real-time conversational experiences — voice agents that respond with imperceptible latency, coding assistants that autocomplete as fast as you can tab, and interactive data analysis that feels instant.

Multi-Agent Systems

Speed unlocks architectural patterns that were impractical with GPU inference. A multi-agent system where five agents need to coordinate in sequence is five times more latency-sensitive. With Groq or Cerebras speed, a five-agent chain completes in the time a single GPU-based agent call used to take.

Speculative Execution

When inference is cheap and fast, you can speculatively generate multiple response candidates in parallel and select the best one. This quality-improvement technique was too expensive with slow inference but becomes practical at Groq/Cerebras speeds.

The GPU Response

NVIDIA is not standing still. TensorRT-LLM optimizations, the Blackwell GPU architecture, and advances in speculative decoding are closing the gap. The competitive pressure from Groq and Cerebras has accelerated GPU inference optimization across the industry — a rising tide effect that benefits everyone building LLM applications.

The inference speed revolution is not about one architecture winning — it is about the entire ecosystem delivering faster, cheaper LLM inference, enabling application patterns that were not feasible two years ago.

Sources:

• https://groq.com/technology/
• https://www.cerebras.net/inference
• https://artificialanalysis.ai/text/arena?tab=Leaderboard