参考リンク
Open AI API Rate Limits: https://platform.openai.com/docs/guides/rate-limits
Project について: https://help.openai.com/en/articles/9186755-managing-your-work-in-the-api-platform-with-projects
lower latency models: https://community.openai.com/t/openai-why-are-the-api-calls-so-slow-when-will-it-be-fixed/148339/87?page=5