Mastering asynchronous patterns in Node.js is essential for building efficient, high-performance applications. Asynchronous programming allows developers to execute non-blocking operations, which results in better resource utilization and improved application responsiveness. A crucial tip for mastering these patterns is to understand the three main approaches: callbacks, promises, and async/await. Each of these can be leveraged in different scenarios, and knowing when to use each method is vital for maintaining clean and manageable code.

When utilizing asynchronous patterns, it’s important to handle potential errors effectively. Implementing proper error handling mechanisms, such as using .catch() with promises or try/catch blocks within async functions, can prevent application crashes and ensure a smoother user experience. Additionally, consider employing libraries like async.js for more advanced control over asynchronous workflows. By applying these tips and techniques, you can enhance the performance and maintainability of your Node.js applications.

When it comes to enhancing the efficiency of your Node.js applications, understanding the power of performance optimization is crucial. Here are the top 5 Node.js performance optimization tricks every developer should know:

1. Use Asynchronous Code: Node.js is built on an asynchronous, event-driven architecture that allows for non-blocking I/O operations. This means utilizing callbacks, promises, and async/await can dramatically boost performance by keeping your application responsive.
2. Optimize the Event Loop: Understanding how the event loop functions is key to optimizing your Node.js application. Avoid heavy computations in the event loop by delegating them to worker threads or utilizing background processing when necessary.

In addition to the first two tricks, the next three should be part of every developer's toolkit:

3. Leverage Caching Strategies: Implementing caching mechanisms, such as Redis or in-memory caches, can drastically reduce load times and improve data retrieval speeds.
4. Minimize Memory Usage: Memory management is critical for performance. Use tools like Node.js's built-in profiler or external libraries to analyze memory usage and identify leaks that could hinder application performance.
5. Use Clustering: To fully utilize multi-core systems, consider employing Node.js's clustering module. This allows you to create multiple instances of your application to handle more requests simultaneously, thereby enhancing throughput and reliability.

Building a scalable REST API with Node.js requires a solid understanding of both the Node.js runtime and RESTful principles. Start by setting up your environment: ensure you have Node.js installed, along with npm for managing packages. In your project directory, initialize a new Node.js project using npm init. Next, you’ll want to choose a web framework that facilitates the creation of RESTful services. The most popular choice is Express.js, which simplifies the process of routing and middleware integration. Be sure to moderate your application’s workload by implementing asynchronous programming with async-await and harness the power of Promises to ensure your API runs smoothly under varying loads.

Once you've set up your basic server structure, it's time to define your resources and endpoints. Use app.get(), app.post(), app.put(), and app.delete() methods to handle CRUD operations for resource management. Consider implementing JWT authentication for secure API access, and create a middleware function that validates tokens on each request. Don't forget to paginate results for large datasets to enhance performance; you can achieve this by adding limit and offset parameters to your query. Finally, document your API with tools like Swagger or Postman to ensure that other developers can easily understand and utilize your API effectively.