ⓘ About these figures: speeds in this guide come from the LLMCheck index. Each is marked: an estimate from the published bandwidth model, a published figure (vendor or press review) or a community run. LLMCheck runs no tests of its own; you can submit a run 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): community79 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): community46 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): sourced48 tok/s (published; BGR, MacStories and Tom’s Hardware reviews)
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 -U mlx-lm
mlx_lm.generate --model mlx-community/Qwen3.6-35B-A3B-4bit \
--prompt "Write a function to sort a linked list" \
--max-tokens 500
The 4-bit conversion is about 20 GB, so it needs a 24 GB Mac or larger; mlx_lm.generate prints the prompt and generation speed when it finishes.
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 3.9x faster LLM prompt processing for the M5 Pro than the M4 Pro, and up to 4x for the M5 Max against the M4 Max (Apple, 3 March 2026; Apple’s own testing, model and settings not stated).
- 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 #1 and its pick for 24–32 GB Macs (on M5 Pro Macs and at 64 GB the pick is LFM2.5-24B-A2B), community79 tok/s
- Gemma 4 26B-A4B — multimodal MoE, estimated~78 tok/s
- Qwen3.8-27B — the strongest dense model in the index, sourced17 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 — small coding MoE, community89 tok/s
- Qwen3.8-Flash-Next at 128GB — community46 tok/s
- DeepSeek V4 Flash at 2-bit, 128GB — community39 tok/s
- Llama 3.3 70B — sourced13 tok/s
M5 Ultra (96–512GB, Mac Studio) — Research Grade
- MiMo-V2.6-Flash — community62 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 | community167 tok/s |
| M5 Max | 32–40 | 614 GB/s | 128 GB | sourced13 tok/s | estimated~82 tok/s |
| M4 Max | 32–40 | 546 GB/s | 128 GB | estimated~12 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 |