Another really important thing that you need to know about Python in Excel is that Microsoft has created a special Python function that is used for interacting with Excel data.

In Python, the mere act of making a function call incurs a relatively large amount of overhead. If some function is called repeatedly in a tight loop, even if it isn’t a long-running function ...

The results of each distributed function are returned as Python objects, so they’re easy to manage and store, and the amount of copying across or within nodes is minimal.