Qwen3.8-Flash-Next Fits on a 48GB MacBook: Pruning + SSD N-gram Table, 39GB RAM
EyalToledano · x · 2026-08-27
Developer Eyal Toledano got Qwen3.8-Flash-Next running on a 48GB MacBook Air: Q4 on MLX uses only 39GB of memory at 28 tok/s decode, and Q8 runs in 50GB. Stock Q4 needs 97GB.
Two stacked tricks:
- REAP pruning cut the expert pool from 68GB to 35GB (288 experts kept);
- The 51B n-gram table now lives on SSD instead of RAM — his patch memmaps the shards, reads 100 bytes per lookup straight off disk, dequantizes on CPU, verified bit-exact against the GPU path.
Results: 288 experts + table on NVMe loads in 6 seconds, 39GB resident, 28 tok/s decode, 600 tok/s prefill, logits identical to the RAM-resident version. Trade-off: HumanEval drops from 93.9% (stock) to 91.5%.
Next up: an MTP drafter and an n-gram lookup drafter for speculative decoding, both built and now benchmarking.
Related event: Developer Prunes 180B-class Qwen MoE to Fit in 48GB of Mac Memory(9 posts)→
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