who has used Python for data analysis (or dealt with data in any form) for even a few weeks, you have almost certainly used Pandas, or at least heard of it.
For more than ten years, Pandas has been the standard library for cleaning data, exploring datasets, and preparing said data for machine learning algorithms. Whether you did that in the context of a university course, a side project, or a full-time job, Pandas has become nearly synonymous with data analysis in Python.
But in recent years, a competitive alternative to Pandas has entered the scene, a library whose name has become more and more frequent in tutorials, GitHub projects, and AI workflows. That library is Polars.
Many developers have adopted Polars as a faster option than Pandas. They used different benchmarks to show good speed boosts, especially when dealing with large datasets. Considering this speed, you might be wondering: If Polars is so much faster, then why isn’t it being used by everybody?
The response is more interesting when we look beyond the advantage of speed. See, Pandas and Polars were based on different philosophies, and it is much more valuable to understand those philosophies than to make a decision based on benchmark figures.
So, in this article we will look at the differences between the two libraries, explain why Polars is usually faster (keyword here: is usually), and show when one library is the better option.
Why Was Polars Created?
When Pandas was first launched in 2008, computers were different; most personal computers had only a small number of CPU cores, the datasets were much smaller, and memory was usually the limiting factor.
So, Pandas was designed with these realities in mind. The API focused on simplicity and readability, allowing users to perform intuitive operations when working with tabular data. Nevertheless, when dataset sizes reached millions of rows, some of Pandas’ original design choices became its limitations.
Today, modern processors have many CPU cores. But traditional Pandas operations normally run on a single core. Moreover, recent programming languages, for example Rust, have made it possible to create faster, safer, and more parallel data-processing libraries.
Polars was designed to take advantage of this new hardware landscape. Rather than trying to replace Pandas feature for feature, it was designed around the idea that modern hardware needs modern software.
At First Glance, They Look Similar
One reason Polars has become so popular is that its grammar feels familiar. For example, loading a CSV file, selecting certain columns, and filtering out certain rows is very similar.
Pandas
Polars
The amount of effort needed to switch between the two libraries when carrying out simple operations is surprisingly small. The actual differences can only be seen if you look below the surface.
People often think that Polars is faster since it was written in Rust. Although Rust does contribute to its performance, it by no means tells the entire story. The reason Polars is fast is due to several architectural choices that combine in order to enhance performance; two important features (in my opinion):
1- Parallel Execution
Polars, unlike Pandas, automatically spreads out many operations over several CPU cores. So, if you are sorting a dataset that has, say, a million rows, rather than having a single worker sort the whole dataset, Polars divides the task among a number of workers who then work at the same time.
2- Lazy Execution
One of the most innovative features of Polars is its lazy execution. Normally, each line of code is carried out right away.
Every operation produces intermediate results. Polars does it differently! Instead of performing each command at once, it creates a query plan that describes all the things you want to achieve.
Only when you request the final result does Polars optimize the entire workflow.
Everything before the .collect() simply describes the computation, and only then does Polars execute the optimized plan. This approach enables Polars to remove unnecessary work before accessing the data.
Memory Matters Too
Performance is not solely a matter of CPU speed. We also need to consider the time needed to move data through the memory. is usually the biggest contributor to total execution time.
The data used by Polars is stored in the Apache Arrow columnar format. This means that instead of storing the information one row at a time, Arrow stores each column as a group. This enables analytical operations to work with neighboring blocks of memory much more efficiently.
It also allows for zero-copy interoperability with many other data-processing libraries. In AI applications that involve feature engineering and preprocessing, this can greatly cut down execution time.
The question now is: Is Faster Always Better?
Short answer: “not necessarily”. Pandas is still one of the most powerful and widely supported libraries within the Python ecosystem. A large number of tutorials, visualization libraries, and machine learning frameworks make the assumption that you are using Pandas.
Pandas is still a very good option for many projects, particularly for those working with small datasets. Polars begins to shine when you start working with datasets that become large, transformations become complex, parallel execution matters, or preprocessing becomes a bottleneck.
Pandas is generally more than enough for exploratory notebooks, teaching, and smaller projects.
Choosing between Pandas and Polars is not an either-or choice. It is still essential to understand Pandas since much of the Python data ecosystem relies on it.
Studying Polars will, however, prepare you for the next generation of data processing. In fact, often, the two libraries exist alongside one another. Analysts develop their ideas using Pandas, while production pipelines are increasingly turning to Polars in order to process larger datasets more efficiently.
It is better to see them as tools rather than as competitors, since they are optimized for different workloads.
Final Thoughts
Polars is a part of a wider trend in software engineering. A trend that follows the advancement in the hardware we use today. Pandas was created in an age when simplicity and flexibility were the main objectives.
Polars was developed during a time when datasets were larger, processors featured dozens of cores, and efficient use of memory became just as important as having clean syntax. That is all to say neither library is better everywhere.
But if you understand the reasons for their differences, you will be in a better position to make decisions, not only when picking a DataFrame library, but each time you are choosing tools for an AI project.
It isn’t always the case that the quickest code is the result of clever algorithms. This is because the software was designed with modern hardware in mind.