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 M3 Ultra 512GB has 384 GB usable, so it fits entirely in memory. Expect about 20 tokens/sec (18–22), with the first token after 0.4 s for a short prompt. This estimate is based on community benchmarks of this exact setup.
| Quantization | File size | Memory | Generation | First token | Source |
|---|---|---|---|---|---|
| UD-IQ1_S | 93.1 GB | Fits | 81 tok/s | 0.4 s | Derived |
| UD-IQ1_M | 97.6 GB | Fits | 78 tok/s | 0.4 s | Derived |
| UD-IQ2_XXS | 101.8 GB | Fits | 75 tok/s | 0.4 s | Derived |
| UD-Q2_K_XL | 108.7 GB | Fits | 70 tok/s | 0.4 s | Derived |
| UD-IQ3_XXS | 120.4 GB | Fits | 63 tok/s | 0.4 s | Derived |
| UD-Q3_K_XL | 147.5 GB | Fits | 51 tok/s | 0.4 s | Derived |
| UD-IQ4_XS | 156.8 GB | Fits | 48 tok/s | 0.4 s | Derived |
| UD-Q4_K_XL | 199.7 GB | Fits | 20 tok/s | 0.4 s | Measured |
| UD-Q5_K_XL | 240.3 GB | Fits | 32 tok/s | 0.4 s | Derived |
| UD-Q6_K_XL | 291.8 GB | Fits | 26 tok/s | 0.4 s | Derived |
| Q8_0 | 341.0 GB | Fits | 22 tok/s | 0.4 s | Derived |
| FP16 | 642.8 GB | Doesn't fit | Won't run | — | — |
All models on the Mac Studio M3 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.