Is GPT-5.4-mini as good as GPT-4o?

For structured, well-prompted tasks with clear constraints, GPT-5.4-mini matches GPT-4o quality in our testing. It struggles more with ambiguous instructions and creative reasoning. The key is constraining what you ask for.

What is OpenAI prefix caching?

OpenAI automatically caches identical prompt prefixes longer than 1024 tokens at a 75% discount. By structuring prompts as static → semi-static → dynamic, you maximize the cacheable prefix and reduce effective input costs by 50-70%.

How much does it cost to run an AI app?

Heavily depends on usage patterns. Arvo's AI costs average ~$0.01 per workout generation after optimization (down from ~$0.04). For a SaaS with 1,000 daily active users, that's ~$10/day or ~$300/month in AI API costs.

We Cut AI Costs by 54% Moving to GPT-5.4-mini

A practical guide to migrating from GPT-4o to GPT-5.4-mini/nano while maintaining quality. Cost routing, prompt restructuring, and the tradeoffs we made.

Arvo Team

10 min read

March 2026

EngineeringCost OptimizationAI

How to reduce OpenAI API costs?

The three most impactful strategies: (1) route simple requests to cheaper models like GPT-5.4-mini/nano, (2) restructure prompts for prefix caching (static content first), and (3) reduce output tokens with structured JSON schemas. We cut costs by 54% combining all three.

TL;DR

•Migrated from GPT-4o to GPT-5.4-mini (primary) and GPT-5.4-nano (simple tasks), cutting average cost per request by 54%.
•Quality remained within 2% on our eval benchmark for structured tasks — the key is highly constrained prompts with clear output schemas.
•Prefix caching saves an additional 50-70% on input tokens by ordering prompts static → semi-static → dynamic.
•Cost routing sends simple requests (2-3 parameters, low ambiguity) to nano, complex requests to mini, and edge cases to the full model.
•Total monthly AI spend dropped from ~$1,200 to ~$550 with no user-visible quality regression.

The Starting Point: $1,200/Month and Growing

Coming soon.

Strategy 1: Model Routing

Coming soon.

Strategy 2: Prompt Restructuring for Prefix Caching

Coming soon.

Strategy 3: Structured Outputs to Reduce Token Waste

Coming soon.

The Migration Process

Coming soon.

What We Lost (and What We Didn't)

Coming soon.

The Numbers: Before and After

Coming soon.

Recommendations for Your AI App

Coming soon.

All costs referenced are based on OpenAI's published pricing as of March 2026. Your mileage will vary based on prompt length, output complexity, and usage patterns. See our developer docs for more on Arvo's architecture.