Main Takeaways
Polars (Rust-based) often outperforms Pandas (Python-based) by 3-10x on large ETL workloads, though gains depend on dataset size and operations.
On smaller data (<1M rows), Pandas may remain competitive and offers better ecosystem integration.
Pandas is still great for familiarity and ecosystem integration, but if your workflows are hitting performance walls, Polars is the better choice for speed and scalability.
Deploying Polars pipelines on Shuttle makes ETL workloads production-ready with minimal overhead.
When your data science workflows start hitting performance walls, the choice between Python's Pandas and Rust's Polars becomes critical. I recently discovered this firsthand while processing millions of rows of data that pushed my Python scripts to their breaking point.
The problem many data engineering teams face today isn't just about handling large datasets; it's about doing it efficiently without burning through compute resources or waiting hours for ETL processes to complete. Traditional Python approaches with Pandas, while familiar and feature-rich, often become bottlenecks as data volumes grow.
This article will walk you through a comprehensive performance comparison between Pandas and Polars using real-world data processing tasks. You'll see exact code implementations, actual benchmark results, and learn how to deploy high-performance data pipelines using Shuttle. The results will change how you approach data processing in production.
Benchmark Dataset: NYC Taxi Trip Data for Real-World ETL
For this comparison, I used the NYC Yellow Taxi dataset from January 2015—12.7 million trip records stored in CSV files totalling about 2.1 GB. This dataset serves as an excellent proxy for real-world ETL challenges that data science teams encounter daily.
The dataset characteristics make it representative of typical production scenarios:
- Scale: 12.7 million rows with 19 columns across multiple data types
- Data quality issues: Missing values, invalid coordinates, and outlier detection requirements
- Mixed operations: Requires loading data, cleaning, aggregations, and complex filtering
- Real-world complexity: Timestamps, geospatial coordinates, and categorical data sources
The ETL pipeline covers five core operations that appear in most data processing workflows:
- Load: Reading CSV data from storage into memory or lazy frames
- Clean: Handling missing data, filtering invalid values, and data type conversions
- Aggregate: Grouping operations across temporal and categorical dimensions
- Filter: Complex multi-condition filtering and sorting operations
- Export: Writing processed results back to storage systems
This represents typical data pipeline tasks in production environments where teams process transaction logs, sensor data, or user behaviour analytics regularly.

Performance Bottlenecks in Python ETL with Pandas
Before diving into solutions, let's examine the specific performance bottlenecks that make Pandas challenging for large-scale data processing operations. These limitations become apparent when working with datasets that exceed available system memory or require complex data transformations.
Eager Loading and Memory Bloat
Pandas uses eager evaluation, meaning every operation executes immediately and creates intermediate results in memory. When you load CSV files, Pandas reads the entire dataset into RAM regardless of whether you'll use all columns or rows:
This eager approach creates memory pressure as each transformation step generates new DataFrames, leading to memory usage that can exceed 2-3x the original dataset size during processing operations.
The Global Interpreter Lock Problem
Python's GIL prevents true multi-threaded execution for CPU-intensive operations, meaning Pandas can only utilize one CPU core at a time for most data processing tasks:
Modern systems with 8, 16, or more CPU cores remain underutilized, creating a significant performance bottleneck for data-intensive operations.
Handling Missing Values and Data Types
Pandas processes missing values through multiple passes over the data, with each operation requiring a full scan of all rows and columns:
These sequential operations become increasingly expensive as datasets grow, particularly when dealing with wide schemas containing many columns with different data types.

How Polars Uses Rust for Fast, Multi-Threaded Data Processing
Polars takes a fundamentally different approach to data processing by leveraging Rust's performance characteristics and implementing lazy evaluation throughout the system. This architecture enables significant performance improvements for ETL operations on large datasets. To understand why polars works so well, let's look at the key features of polars:
Lazy Evaluation and Query Planning
Instead of executing operations immediately, Polars builds a query plan that gets optimized before any actual data processing begins:
This lazy approach allows Polars to analyze the entire pipeline and apply optimizations like predicate pushdown, column pruning, and operation fusion before touching any data.
Query Optimization Techniques
Polars automatically applies several query optimization techniques that reduce I/O operations and memory usage:
Predicate Pushdown: Filters get moved closer to data sources, reducing the amount of data that needs to be loaded:
Column Pruning: Only required columns get loaded from storage, reducing memory usage and I/O:
Multi-Core Processing and Memory Efficiency
Rust's native threading capabilities allow Polars to utilize all available CPU cores automatically. Operations like aggregations, joins, and sorting distribute work across threads without the GIL limitations that constrain Python:
Memory efficiency comes from Rust's ownership system and Polars' streaming capabilities, which process data in chunks rather than loading entire datasets into memory. As the graph belows shows, Polars also maximizes CPU utilization, distributing work across all cores for consistently fast execution.


Pandas vs Polars ETL Pipeline Examples
Let's examine side-by-side implementations of the same ETL pipeline using both libraries. These examples show identical data processing logic implemented with each tool's best practices.
Pandas Implementation: Traditional ETL Approach
Polars Implementation: Lazy ETL Pipeline
Environment Setup for Reproducible Results
To run these benchmarks consistently, I used the following setup:


These side-by-side implementations highlight the key design differences between Pandas and Polars. Pandas follows an eager, memory-intensive approach, while Polars builds an optimized lazy query plan that executes more efficiently. With both pipelines producing the same analytical outputs, the real distinction emerges in how they perform at scale.
Polars vs Pandas Performance on ETL Tasks
After running identical ETL operations on the 12.7 million row NYC taxi dataset, the performance differences are substantial. Here are the detailed benchmark results across all major operations:
Execution Time Comparison
ETL Operation | Pandas (seconds) | Polars (seconds) | Speedup Factor | Notes |
---|---|---|---|---|
Load + Clean | 43.60 | Deferred | - | Polars defers load/clean until execution phase |
Aggregations | 9.21 | 13.80 | 0.67x * | Polars executes load + clean + aggregation together |
Filter + Sort | 9.42 | 5.25 | 1.8x | Polars benefits from predicate pushdown & parallelism |
Export Results | 0.14 | 0.05 | 2.8x | Polars writes faster due to streaming |
Total Pipeline | 62.37s | 19.10s | 3.3x |
*Includes deferred load/clean phase in Polars
Memory Usage Analysis
These results are environment-specific. In practice, Polars often uses 30-60% less memory on large CSV workloads due to column pruning and streaming, though actual savings depend on schema and operations.
Pandas Memory Profile
- Peak usage: 4,658 MB during processing operations
- Memory pattern: Immediate spike during CSV loading
- Garbage collection: Frequent pauses for cleanup
- Intermediate objects: Multiple DataFrame copies in memory
Polars Memory Profile
- Peak usage: ~2,100 MB during aggregation execution
- Memory pattern: Steady increase only during actual processing
- No garbage collection: Rust's ownership system manages memory
- Streaming operations: Data processed in manageable chunks
CPU Utilization Patterns
Polars automatically parallelizes across available cores. Pandas relies on single-threaded execution for most operations unless explicitly offloaded (e.g., via Dask, Modin).
Pandas CPU Usage
- Single-thread utilization: ~12.5% of 8-core system (1 core)
- GIL limitations: Other threads blocked during computation
- Load balancing: Uneven system resource usage
Polars CPU Usage
- Multi-thread utilization: ~85% of 8-core system (all cores)
- Parallel operations: Concurrent processing across cores
- Efficient scheduling: Even load distribution across threads
Why Polars is Faster
The dramatic performance differences stem from fundamental architectural choices. Understanding these differences helps explain when and why you might choose one approach over the other for your data processing systems.
Eager vs Lazy Execution Models
Pandas Eager Execution:
Polars Lazy Execution:
The lazy approach allows Polars to optimize the entire pipeline as a single operation, eliminating intermediate steps and reducing data movement.
Efficient Memory Access Patterns
Polars leverages several memory optimization techniques:
Columnar Data Layout: Data stored column-wise enables better cache locality and vectorized operations.
SIMD Instructions: Single Instruction, Multiple Data processing accelerates numerical computations.
Zero-Copy Operations: Data transformations avoid unnecessary memory allocation when possible.
Streaming Execution: Large datasets are processed in chunks that fit in the CPU cache.
Query Rewriting and Optimization
Polars automatically rewrites queries for better performance:
These optimizations occur automatically, without requiring code changes, making Polars faster while maintaining simplicity. But performance alone isn't the full story. Once you've squeezed every ounce of speed from your ETL pipeline, the next challenge emerges: how do you take that optimized workflow and actually run it in production at scale, reliably, and without DevOps headaches?
Benchmarking on your laptop is one thing; managing deployments, scaling, SSL certificates, and infrastructure is another. That's where Shuttle comes in. With Shuttle, you can deploy your Polars ETL pipeline as a production-ready API in just a few commands, no containers, no load balancers, no endless YAML files.
Deploying a Rust ETL Pipeline with Shuttle
Of course, benchmarks are only half the story. The real challenge is turning a fast local pipeline into something production-ready. That's where Shuttle helps: it lets you deploy Polars pipelines as APIs without wrestling with infra. Traditional Rust deployment can be complex, but Shuttle abstracts away the infrastructure management.
Building a Production ETL API
Here's how to wrap our Polars ETL pipeline in a web API suitable for production use:
Simple Shuttle Deployment Process
Deploying this ETL pipeline to production requires minimal configuration:
1. Deploy with three commands:


Shuttle handles all the complex infrastructure concerns:
- Container orchestration and scaling
- Load balancing and networking
- SSL certificate management
- Monitoring and logging systems
- Automatic deployments from Git
Integration with Data Systems
For production use, you can connect this pipeline to various data sources and destinations:
Migrating from Pandas to Polars: A Practical Guide
The decision to migrate from Pandas to Polars shouldn't be all-or-nothing. Here's a practical approach for teams considering the transition while minimizing risk and disruption.
When to Switch and When to Stick with Pandas
Consider Polars when:
- Processing datasets larger than available RAM
- ETL operations take more than a few minutes to complete
- Memory usage becomes a limiting factor in your systems
- CPU cores remain underutilized during data processing
- You need predictable performance characteristics
Stick with Pandas when:
- Working with datasets under 1GB consistently
- Heavy use of domain-specific libraries that integrate with Pandas
- Rapid prototyping, where development speed matters more than execution speed
- Team lacks Rust experience, and the timeline is tight
- Complex data science workflows with many specialized functions
Hybrid Workflows: Wrapping Heavy Steps in Polars
You don't need to rewrite entire systems. Start by identifying performance bottlenecks and replacing them with Polars operations:
Testing Polars Without Rewriting Your Pipeline
Start with a proof-of-concept approach that validates performance improvements:
Gradual Migration Strategy
Phase 1: Identify bottlenecks
- Profile existing code to find slowest operations
- Measure current memory usage and processing time
- Document data types and transformations used
Phase 2: Proof of concept
- Implement one critical operation in Polars
- Validate identical results between implementations
- Measure performance improvements
Phase 3: Expand coverage
- Replace additional heavy operations
- Build team familiarity with Polars syntax
- Update deployment processes to handle Rust code
Phase 4: Full migration
- Convert remaining operations where beneficial
- Optimize query patterns for maximum performance
- Update monitoring and alerting systems
Final Takeaways
Our benchmarks showed Polars delivering a 3.3x speedup over Pandas for this ETL workload, with significantly lower memory usage and full CPU utilization. This performance comes from its modern architecture: lazy evaluation, query optimization, and native multi-threading powered by Rust.
However, performance isn't everything. Pandas remains the pragmatic choice for smaller datasets (<1 GB), rapid prototyping, and tasks deeply integrated with the broader Python data science ecosystem. In practice, many teams adopt a hybrid strategy: using Polars for heavy data preparation and falling back to Pandas for specialized analysis and ML model integration.
Ultimately, if your current pipelines are hitting performance walls, Polars offers a clear path to faster, more scalable processing. But turning that local speed into a production-ready system presents the next hurdle. This is where Shuttle completes the picture. It abstracts away the complexity of containers and infrastructure, allowing you to deploy a high-performance Polars pipeline as a scalable API in minutes, not days. It turns benchmarks into real-world applications without the DevOps overhead.
Ready to see the difference yourself? Deploy the complete Polars ETL benchmark and run your own comparisons with real data.