GLM 5.3 Flash Q4 @ 60tps / 550tps on M3 Ultra

I have been a dwarfstar fan for awhile and I really liked glm 5.3 flash but needed it to be materially faster to feel good using it. In the screenshot you can see the outcome of using the model with a claude code harness at ~200k depth, with many tool calls and averaging over 38tps output. Yes, I put 60tps in the headline and you will get that if you ask it to write SQL. github.com/IngeniousIdiocy/ds4/blob/glm53-m3ultra/README.md Main ds4 was single-stream serially decoding GLM-5.3-Flash at about 59 percent of the M3 Ultra's measured memory bandwidth. We set an 80 percent target. The big weight-streaming kernels were already efficient, but dozens of small kernels sat between them, each paying latency costs while much of the GPU was idle. We fused that work into larger dispatches and removed separate passes that made the pipeline wait. Result: 29 → 40 t/s at short context, 24 → 38 at 62k, fewer Metal kernels per token, and about 81 percent of the measured bandwidth ceiling. We then attacked the remaining slowdown at very long context. This model's expensive attention computation already works over roughly 2,048 selected positions at both 62k and 300k. What grows is the work of finding those positions in a larger history. The existing implementation sorted and merged increasingly large candidate lists through stages that used very little of the GPU. We replaced that with parallel scans that narrow the candidates before sorting a small surviving list, with the original algorithm handling ambiguous cases. That recovers about one millisecond per generated token. Same positions selected, same order, same outputs. End to end at 300k: stock 21.6 t/s, ours 37.4. Deeper context still costs more to search, but it doesn't multiply the expensive attention work. Prefill started at about 366 t/s at 62k. The big matrix kernels were already efficient, but they wasted time repeatedly unpacking the same weights, fetching data in small pieces, and passing large intermediate results between kernels. We batched more work together, reused prepared weights, widened the loads, and merged passes over the same data. Result: 366 → 550 t/s, a 50% improvement with the same weights, moving the whole pipeline from roughly 51 to 72 percent of the chip's measured matmul ceiling. Cold 62k processing dropped from about 170 seconds to 113. That is the wait every time an agent harness compacts and re-reads its context. The server runs serial unless you pass a drafter file with —dflash. The drafter build recipe is in the repo. The drafter contains an admission policy with a windowed controller that measures its own cost against the serial rate and backs off when it isn't paying. Reasoning tokens decode serially. On a 32-request agent session that's +4 percent over serial. On structured output like SQL and JSON it's +20 to +50 percent. On prose it disengages and costs about 1 percent. Outputs byte-identical to serial decoding on every fixture. Accuracy: on the 100-prompt reference set ds4 uses for release QA, stock scores 0.300804 average NLL against the FP8 reference. This branch scores 0.300766, same 90/100 first-token matches. Nothing here trades quality for speed. This branch is M3 Ultra only because its optimizations depend on detailed measurements of this specific chip: its two-die memory behavior, system-level cache, per-core residency and bandwidth, and how Metal schedules dispatches and threadgroups across its 80 GPU cores. We're optimizing one model's actual execution on one machine, with one set of weights (Q4) and checking that the predicted kernel savings survive in full decoding or prefill.