CodeIgniter's logging system utilizes Buffered Logging to minimize performance overhead. Buffered Logging allows log messages to be accumulated and written to the log file in a batch, reducing the impact on application performance.

Autoloading Helpers in CodeIgniter offers the advantage of reducing code redundancy. By automatically loading frequently used Helpers, developers can streamline their code and make it more concise, leading to better maintainability and readability. This practice also helps in avoiding manual loading of Helpers in every controller, contributing to a more efficient development process.

The correct method to define the sender's email and name in the Email Class is set_sender. This method allows you to specify both the email address and the name of the sender for the outgoing email.

CRUD stands for Create, Read, Update, and Delete. It represents the four basic operations performed on data in a database. Create is used to add new records, Read retrieves data, Update modifies existing records, and Delete removes records. This concept is fundamental to database management and is widely used in CodeIgniter for database operations.

In CodeIgniter, custom libraries are typically placed in the application/libraries directory. This ensures that they are part of the application and can be autoloaded or loaded when needed.

In CodeIgniter, the commonly used method to pass parameters to a library at the time of its loading is $this->load->library('library_name', $params). This method not only loads the specified library but also allows you to pass an array of parameters as the second argument. These parameters can then be accessed within the library's constructor for configuration or customization.

In CodeIgniter, if no method is specified in the URL, the default method called is "index()". It serves as the default action when no specific method is requested. The other options are not the default method names.

When there is a sudden increase in response time for resource retrieval in a CodeIgniter RESTful API, it often indicates a problem with database queries. This could be due to inefficient queries, lack of indexing, or other database-related issues affecting the API's performance. Monitoring and optimizing database queries are crucial in such scenarios.

Token-based validation in forms is a security measure that mitigates Cross-Site Request Forgery (CSRF) attacks. CSRF attacks involve unauthorized actions being performed on behalf of a user without their consent. By using tokens, a unique identifier is generated for each user session, making it challenging for attackers to forge requests.

Compatibility is a key consideration when updating a third-party library in a CodeIgniter application. This ensures that the updated library works seamlessly with the existing CodeIgniter codebase, minimizing disruptions and maintaining application stability.