Step 3.5 Flash – Open-source foundation model, supports deep reasoning at speed

Based on 5 sampled comments from this thread. Analyzed 2026-02-19.

• Praise: Step 3.5 Flash demonstrates impressive context efficiency, allowing full 256k context streams on a 128GB machine, which enhances its usability for complex tasks.
• Praise: The model achieves good inference speeds on Macs, with notable performance metrics like 36 t/s tg and 300 t/s pp, making it practical for real-time applications.
• Praise: Its 51% score on Terminal-Bench 2.0 indicates a solid capability for handling sophisticated, long-horizon tasks, which is crucial for advanced AI applications.
• Praise: The Mixture of Experts architecture allows selective activation of parameters, optimizing performance while maintaining efficiency, which is a significant advancement in model design.
• Concern: The model has a tendency to hallucinate significantly, which raises concerns about its reliability for critical applications and necessitates cautious use.
• Concern: Some users question the relevance of the 51% score on Terminal-Bench 2.0, suggesting it may not adequately reflect the model's stability in handling complex tasks.
• Concern: While the number of parameters is often highlighted, the lack of support for local inference in top models limits their practical applications for many users.