Model comparison
Composer 2 Fast vs GPT-5.5
Head-to-head evidence from 1 shared benchmark result across 1 category. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Composer 2 Fast unranked (Not scored); GPT-5.5 #11 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Composer 2 Fast and GPT-5.5 share 1 comparable benchmark result. 0 of 8 categories are comparable. 0 results are unique to Composer 2 Fast; 52 to GPT-5.5.
Updated July 28, 2026- Shared results
- 1
- Composer 2 Fast only
- 0
- GPT-5.5 only
- 52
- Comparable categories
- 0 / 8
Benchmark data for Composer 2 Fast and GPT-5.5 is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 1 shared benchmark result across 1 evidence category; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM has partial data for these models, but not enough overlapping benchmark coverage to produce a fair score-level comparison yet.
GPT-5.5 has the larger context window at 1M, compared with 200K for Composer 2 Fast.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | Composer 2 Fast | Δ | GPT-5.5 |
|---|---|---|---|
| Agentic | Composer 2 FastNot measured | MarginNo overlap | GPT-5.581.6 |
| Coding | Composer 2 FastNot measured | MarginNo overlap | GPT-5.558.6 |
| Reasoning | Composer 2 FastNot measured | MarginNo overlap | GPT-5.585.0 |
| Knowledge | Composer 2 FastNot measured | MarginNo overlap | GPT-5.557.8 |
| Math | Composer 2 FastNot measured | MarginNo overlap | GPT-5.547.6 |
| Multimodal | Composer 2 FastNot measured | MarginNo overlap | GPT-5.570.4 |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Composer 2 Fast | GPT-5.5 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Composer 2 FastNot available | GPT-5.5$5 input / $30 output | A complete price comparison is not available. |
| Generation speedtokens per second | Composer 2 FastNot available | GPT-5.5Not available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Composer 2 FastNot available | GPT-5.5Not available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Composer 2 Fast200K | GPT-5.51M | GPT-5.5 lists the larger context window. |
Benchmark Deep Dive
Agentic19 benchmarks
| Benchmark | Composer 2 Fast | GPT-5.5 | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | — | 82% | Not comparable |
| CyberGymSource | — | 81.8% | Not comparable |
| BrowseCompSource | — | 84.4% | Not comparable |
| OSWorld-VerifiedSource | — | 78.7% | Not comparable |
| MCP AtlasSource | — | 75.3% | Not comparable |
| ToolathlonSource | — | 55.6% | Not comparable |
| τ²-bench resultsSource | — | 98% | Not comparable |
| AA Agentic IndexSource | — | 44.9% | Not comparable |
| APEX-Agents-AASource | — | 37.7% | Not comparable |
| GDPval-AASource | — | 49.6% | Not comparable |
| GDPval-AASource | — | 1491 | Not comparable |
| Gert LabsSource | — | 72.93% | Not comparable |
| ResearchClawBenchSource | — | 17.0% | Not comparable |
| OSWorld 2.0Source | — | 13.0% | Not comparable |
| JobBenchSource | — | 42.7% | Not comparable |
| ExploitGymSource | — | 13.4% | Not comparable |
| AA AutomationBenchSource | — | 42.1% | Not comparable |
| AA EnterpriseOps-GymSource | — | 46.6% | Not comparable |
| AA ITBenchSource | — | 45.8% | Not comparable |
Coding9 benchmarks
| Benchmark | Composer 2 Fast | GPT-5.5 | Result |
|---|---|---|---|
| React Native EvalsSource | 94.9% | 84.7% | Composer 2 Fast leads |
| SWE-bench ProSource | — | 58.6% | Not comparable |
| Terminal-Bench 2.0Source | — | 82.0% | Not comparable |
| Vibe Code BenchSource | — | 69.85% | Not comparable |
| cursorBench31Source | — | 59.2% | Not comparable |
| cursorBench32Source | — | 58.4% | Not comparable |
| AA Coding IndexSource | — | 74.9% | Not comparable |
| AA-SciCodeSource | — | 56.1% | Not comparable |
| FrontierCode 1.1 MainSource | — | 43.0% | Not comparable |
Reasoning6 benchmarks
Knowledge10 benchmarks
| Benchmark | Composer 2 Fast | GPT-5.5 | Result |
|---|---|---|---|
| GPQASource | — | 93.6% | Not comparable |
| GPQA-DSource | — | 93.6% | Not comparable |
| HLESource | — | 52.2% | Not comparable |
| HLE w/o toolsSource | — | 41.4% | Not comparable |
| Artificial Analysis Intelligence IndexSource | — | 54.8% | Not comparable |
| AA-GPQA DiamondSource | — | 93.5% | Not comparable |
| AA-HLESource | — | 44.3% | Not comparable |
| AA-Omniscience IndexSource | — | 20.1% | Not comparable |
| AA-Omniscience AccuracySource | — | 56.9% | Not comparable |
| AA-Omniscience Hallucination RateSource | — | 85.5% | Not comparable |
Math3 benchmarks
Multimodal5 benchmarks
Inst. Following1 benchmarks
| Benchmark | Composer 2 Fast | GPT-5.5 | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 75.9% | Not comparable |
Frequently Asked Questions (3)
Can I compare Composer 2 Fast and GPT-5.5 on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for Composer 2 Fast and GPT-5.5 today?
GPT-5.5: $5.00 input / $30.00 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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