A recent switch from the main GPT-5 model to the gpt-5-fast variant has provided valuable insights into the capabilities of the latter. While both models have their strengths, differences in behavior and performance are notable.
The primary concern with the original GPT-5 model was its unpredictable behavior, including attempting to run potentially destructive commands. The gpt-5-fast variant appears to address this issue, allowing users to explore the model’s capabilities without risk.
Key advantages of the gpt-5-fast model include its ability to generate better-designed code and recognize potential design flaws in user instructions. This is a significant improvement over Claude 4 Sonnet, which often acts as if it were a junior developer with some skill but limited expertise.
Speed also emerges as a notable benefit of GPT-5, with the gpt-5-fast variant significantly outperforming Claude 3/3.7 in terms of output rate. This faster processing enables users to work more efficiently and explore the model’s capabilities without waiting for results.
While the improvements are incremental rather than revolutionary, they represent a step forward for the technology. The upcoming release of Claude 5 is expected to bring significant advancements, but for now, GPT-5’s gpt-5-fast variant offers a compelling alternative for developers seeking improved performance and design capability.
Source: https://forum.cursor.com/t/is-it-just-me-or-is-gpt-5s-logic-for-code-incredible/128419