knowledge-base/wiki/concepts/llm/coding-benchmark-price-performance.md

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xpost/2026-07-02_atomicchat-coding-benchmark-fable5-gpt55-opus48-glm52.md
concept
llm
coding-benchmark
price-performance
one-shot
fable5
gpt-5.5
opus-4.8
glm-5.2
cost-routing
quality-vs-cost
html5-canvas
physics-simulation

Model Coding Benchmarks — Price-Performance Comparison

TL;DR: One-shot coding tests with identical prompts reveal a 39× cost spread between frontier and budget models — with quality grades only 2 steps apart (A+ to B+). The quality-cost curve is not linear; it's logarithmic. Beyond a certain spend threshold, additional dollars buy diminishing quality gains.

Source

atomic.chat X-Post (01.07.2026)Raw file

Shared by Netbits Stachelbanane (@NetLightning) in OME-Gruppe Topic "News & Infos" on 2026-07-02. Viral: 1.73M views, 4K likes, 2K bookmarks.

The Test

Setup: 4 models, same prompt, one-shot (no iteration), build three self-contained HTML5 canvas scenes with real physics:

  1. Train derailing off a broken bridge into water
  2. Two cars jumping off ramps, colliding mid-air over a canyon
  3. Monster truck crushing a row of parked cars

Why this matters: HTML5 Canvas physics demos are a microcosm of coding-agent tasks — they require spatial reasoning, physics simulation, animation loops, and self-contained output. One-shot means no retry, no refinement — raw generation quality per dollar.

Results

Model Vendor Tokens Cost Grade Cost vs Fable
Fable 5 Anthropic 62,158 $3.12 A+ 1×
GPT 5.5 OpenAI 37,753 $1.14 A 2.7× cheaper
Opus 4.8 Anthropic 22,280 $0.56 5.6× cheaper
GLM 5.2 Z.ai 36,246 $0.08 B+ 39× cheaper

The Quality-Cost Curve

Quality
  A+ |  ● Fable 5 ($3.12)
     |
  A  |       ● GPT 5.5 ($1.14)
     |
  B+ |             ● GLM 5.2 ($0.08)  ← 39× cheaper, only 2 grades down
     |
  B  |  ● Opus 4.8 ($0.56)  ← (grade unspecified, lowest tokens)
     |
     +------+------+------+------+------→ Cost
     $0    $0.50  $1.00  $2.00  $3.00

Key insight: The curve is logarithmic, not linear. Going from B+ to A+ costs 39× more. Going from A to A+ costs 2.7× more. The marginal quality gain per dollar decreases dramatically at the top end.

Cost per 1K Tokens

Model $/1K tokens
Fable 5 $0.050
GPT 5.5 $0.030
Opus 4.8 $0.025
GLM 5.2 $0.002

GLM 5.2's $0.002/1K tokens is the cheapest frontier-level coding generation measured to date.

Community Takeaways

User Insight
@Krysoph GLM 5.2 could improve with iterations + vision model assistance
@suzzvsworld "GLM at $0.08 and still competitive is the real story. Chinese models are making the price conversation impossible to ignore"
@rohanpaul_ai Quality scales with spend; wants test with strict max-token limit
@debugging_yami GPT 5.5 is best value — nearly par with Fable at 1/3 cost

The Three Camps

  1. "Best quality regardless of cost" — Fable 5 wins, but at 39× the price of GLM 5.2
  2. "Best value" — GPT 5.5 at $1.14, 2.7× cheaper than Fable with near-par quality
  3. "Cheapest competitive" — GLM 5.2 at $0.08, 39× cheaper, still produces B+ output

Connection to Existing Wiki Knowledge

Validates: chinese-model-cost-routing.md — The 87% Cost-Cut Playbook

DeRonin's 30-day field report showed 5-12× cost reduction per task category. This benchmark provides an even more extreme data point: 39× cost spread on a single coding task. The pattern holds — Chinese models (GLM 5.2 specifically) deliver near-frontier quality at a fraction of the cost.

Source Cost Spread Task
DeRonin (agent loops) 5× GLM 5.2 vs Sonnet 4.7
DeRonin (reasoning) 11× Kimi K2.7 vs Opus 4.8
atomic.chat (coding) 39× GLM 5.2 vs Fable 5

The 39× spread is the largest measured cost asymmetry in our wiki — an order of magnitude beyond DeRonin's per-task ratios.

Validates: glm-5.2-zai-coding-model.md — GLM 5.2 Deep-Dive

This benchmark adds a fifth independent validation of GLM 5.2's competitive positioning:

  1. IAmFabian's Coding-Tests (14.06.2026) — Flappy Bird + Newton-Pendel
  2. Arnie's 4-Test-Review (22.06.2026) — gemischte Ergebnisse, Frontier-Niveau
  3. Semgrep IDOR-Benchmark (29.06.2026) — Security auf Opus 4.8-Niveau
  4. Artificial Analysis Intelligence Index v4.1 (01.07.2026) — #1 Open-Weights worldwide
  5. atomic.chat One-Shot Coding Benchmark (01.07.2026)B+ at 39× lower cost than Fable 5

Enriches: real-world-coding-showdown.md — Methodology

Fahd Mirza's Hermes Agent showdown used head-to-head methodology (same agent, same task, different models). atomic.chat's benchmark is a simpler variant: same prompt, no agent framework, raw one-shot output. Both complement standard benchmarks (SWE-bench, HumanEval) by testing real generation quality.

Methodology Source Scope
Standard benchmark SWE-bench Pro, HumanEval Narrow, reproducible
Agent-framework showdown Fahd Mirza (Hermes) Multi-file, tool-use, real app
One-shot raw generation atomic.chat Single prompt, self-contained output

Connects: ai-investment-bubble.md — Cost Pressure Narrative

The 39× cost spread is ammunition for the "AI is overbuilt" thesis: if a B+ model costs $0.08 and an A+ model costs $3.12, the economic case for premium models erodes when B+ is "good enough" for most use cases. This mirrors Meta selling excess compute capacity and Oracle warning of datacenter delays — the market is pricing in overinvestment in premium AI.

Implications for Our Routing Architecture

See ../../architecture/model-routing.md.

Task Tier Recommended Model Rationale
Tier 4 (Frontier quality) Fable 5 or Opus 4.8 When A+ is non-negotiable
Tier 3 (High quality) GPT 5.5 Best value — A at 2.7× cheaper
Tier 2 (Standard) GLM 5.2 B+ at 39× cheaper — "good enough" for most
Tier 0-1 (Bulk) GLM 5.2 or MiMo Cheapest viable option

New insight: The atomic.chat benchmark suggests GPT 5.5 may be the sweet spot for quality-sensitive tasks where Fable 5's premium is unjustified. Our current routing uses GLM 5.2 as primary — this benchmark validates that for most tasks (Tier 0-2), but suggests GPT 5.5 as a Tier 3 upgrade path.

Methodology Limitations

  1. One-shot only — No iteration, no refinement. Real coding workflows involve multiple rounds. @Krysoph notes GLM 5.2 could improve with iterations.
  2. No strict token limit — @rohanpaul_ai wants to see results with a max-token constraint. Without one, Fable 5's 62K tokens may reflect verbosity, not capability.
  3. Subjective grading — A+/A/B+ grades are atomic.chat's assessment, not a standardized rubric.
  4. Single task type — HTML5 Canvas physics is one domain. Results may not generalize to backend logic, data analysis, or agentic tool-use.
  5. Opus 4.8 grade missing — The post doesn't specify Opus 4.8's quality grade, only its cost/token count.

Cross-References

External Sources