When it comes to modern web development, the choice of the right JavaScript framework can greatly influence the efficiency and scalability of your application. In this comparison, we will explore the top 5 JavaScript frameworks: React, Angular, Vue.js, Ember.js, and Svelte. Each framework offers unique features that cater to different project requirements, making it essential to choose one that aligns with your goals.

1. React: Known for its component-based architecture, React allows developers to create reusable UI components, making it perfect for large applications.
2. Angular: A full-fledged MVC framework, Angular provides a comprehensive solution with two-way data binding and dependency injection.
3. Vue.js: Renowned for its simplicity and flexibility, Vue.js is great for both small and large-scale applications, offering an approachable learning curve.
4. Ember.js: If you're looking for convention over configuration, Ember.js provides a robust framework that emphasizes best practices.
5. Svelte: Svelte shifts much of the work to compile time, resulting in faster applications and an uncomplicated coding experience.

When it comes to modern web development, React, Angular, and Vue are three of the most popular JavaScript frameworks used by developers worldwide. Each framework has its unique characteristics and applications that cater to different project requirements. React is a library for building user interfaces, emphasizing a component-based architecture to enhance reusability and performance. Angular, on the other hand, is a full-fledged MVC framework that offers a comprehensive suite of tools for building robust applications, providing features like dependency injection and two-way data binding out of the box. Lastly, Vue strikes a balance between the two, being incrementally adoptable, which allows developers to integrate it seamlessly into existing projects or use it to build standalone applications.

Understanding the key differences between these frameworks is essential for making informed decisions in your development process. Here’s a quick comparison:

• Learning Curve: React has a relatively gentle learning curve, while Angular's complexity can be daunting for beginners. Vue offers a middle ground, being straightforward yet powerful.
• Performance: While all three frameworks offer high performance, React excels in dynamic rendering with its virtual DOM. Angular may lag in performance due to its digest cycle, while Vue provides a faster two-way data binding mechanism.

Choosing the right framework depends on your specific project needs, development team expertise, and scalability requirements.

When considering a switch in frameworks, it's essential to evaluate both performance and usability. A framework's performance directly impacts load times, responsiveness, and ultimately, user satisfaction. If your current framework is causing significant lag or bottlenecks, it may be time to look for more efficient alternatives. Benchmark tests can help you analyze metrics such as speed, resource consumption, and scalability, offering clear indicators of whether a change is required. This evaluation helps ensure that you are not only keeping up with competitors but also providing the best possible experience for your users.

On the other hand, usability is equally vital, affecting how developers and users interact with your application. A user-friendly framework can dramatically increase productivity, reduce the learning curve for new team members, and improve collaboration. Frameworks that prioritize usability often come with extensive documentation, active community support, and intuitive structures that streamline development processes. If you find that your current framework is hindering productivity or making it difficult for your team to implement new features, it may indeed signal the need for a switch. In evaluating both performance and usability, the right choice will set the foundation for your project's success.