ⓘ About these figures: speed and score numbers in this guide are LLMCheck index estimates (est.) derived from our published methodology — not lab measurements. Community-verified runs are invited via /contribute.
Why Memory Bandwidth Is Everything
According to the LLMCheck index, LLM inference is memory-bandwidth bound, not compute-bound. Every token generated requires reading the entire model's weights from memory once. The speed at which your Mac can shuttle data from Unified Memory to the GPU determines your tokens-per-second ceiling.
This is why the M5 Max’s 614 GB/s — 12% more than the M4 Max’s 546 GB/s — translates directly into decode speed: about 10–12% faster for the same model, a little less for small ones. The M5 generation’s larger gain is in prompt processing, covered below.
The ceiling: tokens per second cannot exceed memory bandwidth divided by the bytes read per token. Real decode reaches roughly 78% of that on large models, plus a small fixed cost per token — the two-term model behind every LLMCheck estimate.
M5 Family Specs at a Glance
M5 (Base)
- Memory: 16GB / 24GB / 32GB Unified Memory
- Bandwidth: 153 GB/s
- GPU cores: 10, each with a Neural Accelerator
- Best for: 7–12B models at Q4, Gemma 4 12B, GPT-oss 20B
- Qwen 3.5 9B (Q4): estimated~23 tok/s
M5 Pro
- Memory: 24GB / 48GB / 64GB Unified Memory
- Bandwidth: 307 GB/s
- GPU cores: 16–20
- Best for: 30B-class MoE models, 27B dense, 70B dense at 64GB
- Qwen 3.6-35B-A3B (Q4): estimated~92 tok/s
M5 Max
- Memory: 36GB / 48GB / 64GB / 128GB Unified Memory
- Bandwidth: 614 GB/s (460 GB/s on the 32-core GPU)
- GPU cores: 32–40
- Best for: the 100B+ MoE tier at 128GB, 70B dense
- Qwen3.8-Flash-Next (Q4): estimated~49 tok/s
M5 Ultra (Mac Studio, September 2026)
- Memory: 96GB / 256GB / 512GB Unified Memory
- Bandwidth: 1,228 GB/s (Apple: 1.2 TB/s)
- GPU cores: 64–80
- Best for: 4-bit frontier MoE (MiMo-V2.6-Flash, GLM-5.3-Flash), GLM-5.3 at 512GB
- Qwen3.8-27B (Q4): sourced~55 tok/s (BGR review)
Estimated Performance: M5 Max vs M4 Max
Corrected 23 September 2026: an earlier version of this section presented a table of M5 Max vs M4 Max results as tests run by LLMCheck, showing gains of about 28%. LLMCheck does not run lab tests, and a 28% decode gain is not consistent with the two chips’ roughly 12% difference in memory bandwidth. The section now gives the index’s estimates, labelled as such.
Token generation on Apple Silicon is bound by memory bandwidth. The M5 Max has about 12% more of it than the M4 Max (614 vs 546 GB/s), so for the same model at the same quantization the LLMCheck index estimates decode roughly 7–12% faster — for example Qwen3.8-27B at ~29 vs ~26 tok/s (estimated, 4-bit). Small models gain slightly less, because a fixed per-token overhead dominates their decode time.
The M5’s larger improvement is in prompt processing, where the new GPU Neural Accelerators do the work: time to first token on long prompts falls far more than decode speed rises. The first independent reviews of the M5 Ultra show the same split — see M5 Ultra and M6, measured. Every figure for both chips is on the benchmarks page, marked with its provenance.
MLX Framework: The M5 Advantage
Apple’s MLX framework is purpose-built for Apple Silicon and it shows: it often decodes about 20% faster than llama.cpp for the same model — one published comparison measured 110 vs 90 tok/s for Qwen 3 30B-A3B on an M4 Max (arXiv 2601.19139).
- Why MLX is faster: It uses Metal kernels tuned for Apple’s GPU — including, on M5, the Neural Accelerators in each GPU core — and avoids the abstraction layers that llama.cpp uses for cross-platform compatibility.
- When to use MLX: If you are on Apple Silicon and prioritize raw speed. The MLX ecosystem includes
mlx-lmfor text generation,mlx-vlmfor vision models, andmlx-whisperfor audio. - When to use llama.cpp/Ollama: If you need the broadest model compatibility, the Ollama model library, or plan to run on non-Apple hardware as well.
# Quick MLX benchmark on your M5 Mac
pip install mlx-lm
mlx_lm.generate --model mlx-community/Qwen3.5-30B-A3B-4bit \
--prompt "Write a function to sort a linked list" \
--max-tokens 500 --verbose
Neural Accelerators, Not the Neural Engine
The M5 generation’s AI upgrade is in the GPU: every GPU core now has a Neural Accelerator, dedicated matrix hardware. Apple quotes up to 4x faster LLM prompt processing for the M5 Pro and M5 Max than for the M4 Pro and M4 Max.
- Prompt processing (prefill): the big gain — long prompts and documents start answering far sooner. MLX reaches the Neural Accelerators through Metal.
- Token generation (decode): still bound by memory bandwidth, so it tracks the 12% bandwidth gain.
- The Neural Engine (16-core) is a separate block used by Core ML and Apple Intelligence; neither MLX nor llama.cpp runs LLM decode on it.
Model Recommendations per M5 Variant
Based on the LLMCheck index, here is what to run on each M5 chip:
M5 (16–32GB) — Daily Driver Models
- Gemma 4 12B — text, image and audio in about 7GB, estimated~17 tok/s
- GPT-oss 20B — OpenAI’s open MoE, fits 16GB, estimated~41 tok/s
- Qwen 3.5 9B — estimated~23 tok/s
- Qwen 3.6-35B-A3B at 32GB — estimated~59 tok/s
M5 Pro (24–64GB) — Power User Models
- Qwen 3.6-35B-A3B — the index’s #2 model, estimated~92 tok/s
- Gemma 4 26B-A4B — multimodal MoE, estimated~72 tok/s
- Qwen3.8-27B — the strongest dense model in the index, estimated~15 tok/s
- Qwen3-Coder-Next at 64GB — 80B coding MoE, estimated~49 tok/s
M5 Max (36–128GB) — Frontier Local AI
- KAT-Coder-V2.5 — the index’s #1, estimated~117 tok/s
- Qwen3.8-Flash-Next at 128GB — estimated~49 tok/s
- DeepSeek V4 Flash at 2-bit, 128GB — community~39 tok/s
- Llama 3.3 70B — estimated~12 tok/s
M5 Ultra (96–512GB, Mac Studio) — Research Grade
- MiMo-V2.6-Flash — estimated~42 tok/s
- GLM-5.3-Flash at 4-bit — estimated~35 tok/s
- GLM-5.3 at 512GB — estimated~17 tok/s
- Serve models to a local team through an OpenAI-compatible API
Not sure which M5 variant matches your needs? Use the Best-by-Mac rankings or the Mac Advisor for your exact configuration.
Single-stream decode at 4-bit (DeepSeek V4 Flash at 2-bit) from the LLMCheck index — estimated unless marked; Llama 3.3 70B and Qwen 3.5 9B columns below likewise.
| Chip | GPU cores | Bandwidth | Max RAM | Llama 3.3 70B | Qwen 3.5 9B |
|---|---|---|---|---|---|
| M5 Ultra | 64–80 | 1,228 GB/s | 512 GB | estimated~23 tok/s | estimated~146 tok/s |
| M5 Max | 32–40 | 614 GB/s | 128 GB | estimated~12 tok/s | estimated~82 tok/s |
| M4 Max | 32–40 | 546 GB/s | 128 GB | estimated~11 tok/s | estimated~74 tok/s |
| M2 Ultra | 60–76 | 800 GB/s | 192 GB | estimated~15 tok/s | estimated~103 tok/s |
| M3 Max | 30–40 | 400 GB/s | 128 GB | estimated~8 tok/s | estimated~56 tok/s |
| M5 Pro | 16–20 | 307 GB/s | 64 GB | estimated~6 tok/s | estimated~44 tok/s |
| M4 Pro | 16–20 | 273 GB/s | 64 GB | estimated~5 tok/s | estimated~39 tok/s |
| M3 Pro | 14–18 | 150 GB/s | 36 GB | Doesn’t fit | estimated~22 tok/s |