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// RUN — FITS
Can the Apple M1 Ultra 128GB run LongT5?
Yes — here's how fast and up to what context, with real measured numbers.
LongT5 on the Apple M1 Ultra 128GB
| Quant | Fits? | Max context | Speed | Beyond context |
|---|---|---|---|---|
| FP16 | yes | 1643k | 90.7-109.3 t/s | ~1.1-1.4 (slow) |
| Q8 | yes | 1689k | 181.3-218.7 t/s | ~2.3-2.7 (slow) |
| Q4 | yes | 1709k | 323.8-390.5 t/s | ~4-4.9 (slow) |
Estimate (memory-bound). Beyond "max context" the KV cache spills to SSD swap and speed drops to the "beyond" figure.
FAQ
Can the Apple M1 Ultra 128GB run LongT5?▶
Yes. At Q4 it generates ~323.8-390.5 tok/s and fits up to 1709k context; beyond that it spills to SSD swap and slows to ~4-4.9 tok/s.
How much context fits?▶
At Q4, up to about 1709k tokens stay in fast memory; longer context spills to SSD swap and throughput collapses.