Legacy Code Refactoring

Act as a Senior Python Engineer. Refactor the provided legacy code block.

Context:

• The current code is slow and hard to read.
• It processes large CSV files sequentially.
• Target environment: Python 3.12.

Requirements:

1. Implement vectorization using Pandas where possible.
2. Add type hinting (PEP 484).
3. Add docstrings following the Google style guide.
4. Handle 'FileNotFound' and 'EmptyData' exceptions gracefully.

Code to refactor: [PASTE CODE HERE]

Output format:

• The refactored code block.
• A bulleted list of the performance improvements made.