Ruby on Rails remains a popular choice for web development in 2023 due to its robust set of features and simplicity. This framework embraces the principles of convention over configuration, allowing developers to quickly prototype and build fully functional web applications. As businesses continue to seek rapid deployment and scalability, Rails' built-in tools streamline the development process, ensuring that teams can deliver high-quality products in a timely manner. Moreover, the vibrant community surrounding Ruby on Rails provides extensive documentation, libraries, and resources that make it easier for newcomers and seasoned developers alike to enhance their skills and tackle complex projects.

Another reason Ruby on Rails is still highly regarded is its emphasis on testing and maintainability. With a strong focus on test-driven development (TDD), Rails encourages developers to write tests alongside their code, leading to fewer bugs and a more predictable codebase. This practice not only improves the quality of the finished product but also makes future updates and maintenance more manageable. Furthermore, as the demand for sustainable web applications increases, Rails' focus on clean, readable code aligns perfectly with the industry's push for better software practices.

When it comes to building robust applications with Ruby on Rails, leveraging the power of gems can greatly enhance functionality and streamline development. Here are 10 essential gems that every Rails developer should consider integrating into their projects:

1. Devise: For user authentication, making it easy to set up a full-featured user management system.
2. Pundit: A gem for handling authorization, helping manage who can perform certain actions in your application.
3. ActiveAdmin: To create an elegant admin dashboard for managing models without extensive coding.
4. Paperclip: Allows easy file uploads and management, ideal for handling attachments.
5. Kaminari: A powerful pagination gem to enhance the user experience with large datasets.

In addition to the first five, here are five more gems that can take your Ruby on Rails application to the next level:

6. Sidekiq: For background job processing, it allows asynchronous tasks to run smoothly.
7. CarrierWave: Another gem for file uploads, giving you more flexibility and control.
8. SimpleCov: A code coverage analysis tool that helps keep your test suite robust.
9. Ransack: For advanced searching and filtering capabilities, enabling users to find data easily.
10. Faker: A gem to generate fake data for testing and development purposes.

Optimizing performance in Ruby on Rails is essential for building scalable applications that can handle high traffic smoothly. One of the best practices is to minimize database queries by utilizing ActiveRecord wisely. This includes using methods like includes and joins to avoid the 'N+1 query' problem. Additionally, implementing caching strategies, such as fragment caching or page caching, can significantly reduce the load time by storing frequently accessed data and serving it without repeated database calls.

Another key aspect of performance optimization in Ruby on Rails is the proper use of background jobs. By offloading time-consuming processes to background workers (using tools like Sidekiq or Resque), you can enhance the responsiveness of your application. Moreover, consider using a Content Delivery Network (CDN) to serve assets, which helps in decreasing latency and improving load times for users around the globe. Regularly profiling your application with tools like Bullet or New Relic will also help identify bottlenecks and areas for further optimization.