GLM-5.3 Flash is a 321.3B-parameter mixture-of-experts model (18B active per token). At UD-Q4_K_XL it needs about 200.5 GB of memory. The Mac Studio M5 Ultra 512GB has 384 GB usable, so it fits entirely in memory. Expect about 51 tokens/sec (43–58), with the first token after 0.3 s for a short prompt. This estimate is projected from the hardware specs; no benchmarks exist yet.
| Quantization | File size | Memory | Generation | First token | Source |
|---|---|---|---|---|---|
| UD-IQ1_S | 93.1 GB | Fits | 109 tok/s | 0.3 s | Projected |
| UD-IQ1_M | 97.6 GB | Fits | 104 tok/s | 0.3 s | Projected |
| UD-IQ2_XXS | 101.8 GB | Fits | 99 tok/s | 0.3 s | Projected |
| UD-Q2_K_XL | 108.7 GB | Fits | 93 tok/s | 0.3 s | Projected |
| UD-IQ3_XXS | 120.4 GB | Fits | 84 tok/s | 0.3 s | Projected |
| UD-Q3_K_XL | 147.5 GB | Fits | 68 tok/s | 0.3 s | Projected |
| UD-IQ4_XS | 156.8 GB | Fits | 64 tok/s | 0.3 s | Projected |
| UD-Q4_K_XL | 199.7 GB | Fits | 51 tok/s | 0.3 s | Projected |
| UD-Q5_K_XL | 240.3 GB | Fits | 42 tok/s | 0.3 s | Projected |
| UD-Q6_K_XL | 291.8 GB | Fits | 35 tok/s | 0.3 s | Projected |
| Q8_0 | 341.0 GB | Fits | 30 tok/s | 0.3 s | Projected |
| FP16 | 642.8 GB | Doesn't fit | Won't run | — | — |
All models on the Mac Studio M5 Ultra 512GB · GLM-5.3 Flash on all hardware
Estimates for a short prompt on a single device. Measured numbers come from community benchmarks (r/LocalLLaMA, localscore.ai and more); others are derived from similar setups or projected from specs. Open source on GitHub.