Andre Rucker for BI Pinterest's VP of product management said mixing open-source and closed-source AI models helped cut costs. The social platform's recent AI-enabled features combine OpenAI, Alibaba, and its own AI models. To support this approach, Pinterest invested in cloud infrastructure and an updated hiring strategy. In its pursuit of creating AI-supported tools for its users and advertisers, Pinterest leaders said it is actually shrinking part of its AI budget. As companies continue to spend on AI, they face pressure from investors to show returns on investment from this fast-evolving technology. One way to do that: Stretch investments by shrinking the budget needed for the systems that power AI features. Pinterest, the visual-first social media platform where users can save images to curate their ideas, is taking what it calls a "model-agnostic" approach to generative AI, said Vicky Gkiza, the company's vice president of product management.…