A backend engineering team inherited a costly search ranking pipeline using GPT-4o for classification and re-ranking. They conducted a month-long production experiment rerouting 10% of traffic to cheaper models DeepSeek V4 Flash and Gemini 2.0 Pro, comparing latency, throughput, quality (via human evaluation), and cost. DeepSeek V4 Flash achieved similar quality (4.23/5 vs GPT-4o 4.48/5) at roughly one-tenth the cost, with acceptable latency and throughput. The team implemented caching, streaming, and tiered model usage to optimize costs and maintain quality, resulting in an 89% cost reduction with no measurable quality regression in production.

Jun 13, 2026, 6:30 PM