Hiring a Hazelcast developer can significantly boost your project’s performance. They are proficient in implementing in-memory data grids (IMDG), which can drastically improve application speed and scalability. Their expertise in distributed computing helps in managing large data sets across clusters, offering fault tolerance and resilience. They can also effectively utilize Hazelcast's features like distributed caching, messaging, and NoSQL support, optimizing your system's performance. Lastly, a Hazelcast developer can provide real-time processing and low latency solutions for high-transactional, data-intensive applications. This can be particularly beneficial for businesses dealing with big data or real-time analytics.