Excel Speed Optimization

I'm struggling with a slow Excel file that takes around 20 minutes for each change. I suspect the volume of data, with thousands of rows/columns, might be the issue. The formulas, although not overly complex or extensive, may also be contributing to the sluggish performance.

I need help from an Excel expert who can:

- Diagnose the root cause of the slowness
- Streamline and optimize the file for better performance

Ideal Skills:
- Expert in Excel operations
- Transfer large data sets efficiently
- Understanding of excel formulas and functions
- Dexterity in spotting and rectifying errors
- Good problem-solving skills to identify and fix issues