如何使用熊猫来编写数据处理代码，使其至少具有与手写的标准Python代码相同的高性能?

I have a machine learning application written in Python which includes a data processing step. When I wrote it, I initially did the data processing on Pandas DataFrames, but when this lead to abysmal performance I eventually rewrote it using vanilla Python, with for loops instead of vectorized operations and lists and dicts instead of DataFrames and Series. To my surprise, the performance of the code written in vanilla Python ended up being I have a machine learning application written i