I have extensive experience with Apex and Visualforce, having developed multiple custom solutions in Salesforce. My projects include creating custom controllers and triggers in Apex to handle complex business logic, and designing user interfaces with Visualforce to enhance user experience. I've also integrated these components with external systems using REST and SOAP APIs, ensuring seamless data flow and functionality.

I prioritize code quality by following best practices such as using version control systems like Git, writing unit tests with Apex Testing Framework, and conducting regular code reviews. I also adhere to Salesforce's coding standards and use tools like Salesforce DX for continuous integration and delivery, which helps in maintaining a clean and efficient codebase.

To optimize performance, I focus on efficient query execution by using indexed fields, minimizing the number of queries, and leveraging batch and queueable Apex for bulk operations. I also monitor and analyze application performance using Salesforce's built-in tools like Performance Monitoring and Debug Logs, which helps in identifying and resolving bottlenecks.

I ensure data security by implementing robust access controls, using field-level security, and role-based permissions. I also stay updated with Salesforce's security features and compliance standards, such as GDPR and SOC 2, to ensure that all data handling practices are in line with legal requirements and industry best practices.

One challenging project involved integrating a legacy system with Salesforce, which required extensive data mapping and custom development. I overcame this by designing a flexible integration framework using middleware like MuleSoft, which facilitated smooth data synchronization and reduced downtime. This approach not only met the project's technical requirements but also improved overall system efficiency.