Source Code Acquisition for VB.NET Project

I have an executable file of a Visual Basic project and need the complete source code to make modifications. In particular, I need assistance with optimizing the code. The main tasks will include:

- Analyzing the existing code for potential improvements
- Implementing changes to enhance performance speed, memory usage, and algorithm efficiency
- Ensuring the modified code still functions correctly

Ideal skills and experience for the job include:
- Proficiency in VB.NET
- Previous experience with code optimization
- Ability to work with existing code and modify it as necessary
- Strong problem-solving skills