DeepSeek V4 Flash vs Pro: Flash Finds 100% of Bugs, Pro Outputs 2.4x More
TheDeepArchive · reddit · 2026-08-13
Methodology
A developer built a rigorous benchmark comparing DeepSeek V4 Flash (0731) and DeepSeek V4 Pro (0813) on a real-world Python+PySide6 desktop app codebase.
The test covered 6 task types: architecture review, fact-flow tracing, live bug hunt, refactoring plan, instruction-conflict test, and impact analysis. 18 runs were conducted, extracting 239 atomic claims verified independently by Qwen 3.7 Plus.
Key Findings
- Factual Accuracy: Both models are nearly identical (Pro 95.9%, Flash 95.7%). Pro had zero hard factual errors.
- Output Volume: Pro generated significantly more verifiable claims (169 vs 70, a 2.4x difference).
- Bug Hunting: Flash impressively found all 3 known latent bugs, while Pro only caught 1.
- Consistency: Pro showed low run-to-run consistency, with depth varying 2.7x between runs.
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