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Engine comparison benchmark — TensorSharp vs llama.cpp vs vLLM

Same GGUF files, same host, one uniform OpenAI /v1/chat/completions surface, across text / image / audio / video / single-turn / multi-turn / function-call / structured-output scenarios on the selected compute backends (ggml_cuda / ggml_vulkan / ggml_metal / ggml_cpu / cpu / ...).

Numbers are tokens/second (higher is better). — = not applicable / skipped, fail = errored at runtime, n/a = combination never attempted.

Software / hardware

Component Version / detail
TensorSharp git a8d8f40, .NET 10.0.204 (backends: ggml_cuda / ggml_vulkan / ggml_metal / cuda / mlx / ggml_cpu / cpu)
llama.cpp C:\Works\llama.cpp\build-cuda\bin\Release\llama-server.exe
vLLM endpoint http://127.0.0.1:8000 (connect-only)
GPU NVIDIA GeForce RTX 3080 Laptop GPU, 16384 MiB

Methodology

  • Each (engine, backend, model) group launches its server once; all of that group's scenarios run against it, so per-scenario timings exclude model-load cost.
  • Metrics come from the streamed response: ttft is time-to-first-token (prefill latency proxy), prefill_tps = prompt_tokens / ttft, and decode_tps = (completion_tokens - 1) / (t_last - t_first).
  • DiffusionGemma denoises whole blocks (no token stream), so it is run non-streaming and its decode_tps is wall-clock tokens/second.
  • Greedy sampling (temperature=0); one warmup request per server is discarded.
  • The headline per-engine tables are the single-stream, MTP-off baseline. MTP on/off and parallel-request scaling are reported in their own sections below.

Performance ratio — TensorSharp vs reference engines

Geomean of TensorSharp's per-scenario speedup over each reference engine on the same backend, across every scenario both engines ran (single-stream, MTP-off). A value > 1.0× means TensorSharp is faster (for decode / prefill throughput) or lower-latency (for TTFT); — = no overlapping cells. Per-scenario ratios are in each model's section below.

No overlapping TensorSharp / reference cells to compare.

Gemma 4 26B-A4B it (QAT UD-Q4_K_XL, MoE) (gemma4-26b-a4b)

Decode throughput (tok/s)

Scenario TensorSharp · CUDA TensorSharp · Direct CUDA
text_short 78.7 35.3
text_long 78.4 38.5
multi_turn 79.1 38.5

Prefill throughput (tok/s)

Scenario TensorSharp · CUDA TensorSharp · Direct CUDA
text_short 1832.1 128.2
text_long 1847.3 48.0
multi_turn 1940.7 114.2

Time to first token (ms, lower is better)

Scenario TensorSharp · CUDA TensorSharp · Direct CUDA
text_short 1078.0 15407.0
text_long 1703.0 65532.0
multi_turn 1079.0 18329.0

Qwen 3.6 35B-A3B (UD-IQ2_XXS, MoE) (qwen36-35b-a3b)

Decode throughput (tok/s)

Scenario TensorSharp · CUDA TensorSharp · Direct CUDA
text_short 73.9 24.4
text_long 76.6 23.5
multi_turn 76.7 25.0

Prefill throughput (tok/s)

Scenario TensorSharp · CUDA TensorSharp · Direct CUDA
text_short 1472.8 270.4
text_long 1690.1 267.4
multi_turn 1702.4 263.4

Time to first token (ms, lower is better)

Scenario TensorSharp · CUDA TensorSharp · Direct CUDA
text_short 1360.0 7407.0
text_long 1891.0 11954.0
multi_turn 1250.0 8078.0

Output quality — TensorSharp vs llama.cpp

Both engines decode the same GGUF greedily (temperature=0) on the same backend, so their outputs should agree closely. similarity is a whitespace-normalized SequenceMatcher ratio between the two outputs (1.00 = identical); low similarity, an invalid JSON object in json_mode, or a missing tool call in function_call flags an output-quality problem on one side. Prefill scenarios (8-token outputs) are excluded. Side-by-side excerpts follow the table, lowest agreement first.

No overlapping ok cells with captured output to compare.

MTP / NextN speculative decoding (on vs off)

Single-stream decode tok/s with MTP/NextN speculative decoding off vs on (TensorSharp only). Speedup < 1.0× means speculation cost more than it saved for that cell — expected when the fused full-model decode path is already the fast path.

No MTP on/off pairs were run (use --mtp off,on).

Parallel-request scaling (concurrency)

decode/req is the mean per-request decode tok/s; aggregate is the system-wide decode throughput (total generated tokens / the wall window during which any sequence was decoding) when N identical requests are fired at one server at once.

No parallel-request cells were run (use --concurrency 1,4,8).

Function-calling correctness

No function-call cells were run.