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tech 12 September 2026

Understanding Compile Times: Buildprof Tool for Bun

Learn how 'buildprof', an open-source tool, helps visualize and optimize software compile times, using Bun as an example.

Article inspired by the original source
I made a build visualizer to understand Bun’s compile times ↗ lalitm.com

Introduction

In the realm of software development, compile speed is a crucial factor that can affect developer productivity and the efficiency of development cycles. For tech decision-makers and developers, understanding bottlenecks in the compilation process can lead to significant optimizations. This is where 'buildprof', an open-source tool, comes into play, helping visualize compile times and identify improvement opportunities.

Why Visualizing Compile Times is Crucial

Slow compile times are not only frustrating, but they also hinder development teams from reaching optimal productivity. According to a recent study, over 30% of developers believe that faster compile times could enhance their daily efficiency. However, the cause of slowdowns often remains obscure. With 'buildprof', every process launched by a build command is recorded and visualized on a single timeline, enabling deeper analysis.

Bun Example: A Practical Use Case

Lalit Maganti designed 'buildprof' to better understand why Bun's new Rust build was faster than its old Zig build. Using scripts to reproduce builds on a Linux machine, he discovered significant differences in compile times:

  • Zig Build (Full LTO): 30 minutes 06 seconds
  • Rust Build (ThinLTO): 5 minutes 37 seconds

This drastic difference led to further investigation. By comparing these two approaches, Maganti identified that link-time optimization (LTO) played a crucial role.

Benefits of Link-Time Optimization (LTO)

LTO allows compilers to optimize beyond individual compilation units. Full LTO brings all units together into one massive optimization task, while ThinLTO preserves some separation to allow parallel execution. This distinction is essential for improving compile times while maintaining efficient resource utilization.

How to Use 'buildprof'

Using 'buildprof' is straightforward: simply prefix your build command with buildprof --. Here are some examples:

  • buildprof -- make -j16
  • buildprof -- cargo build

By integrating 'buildprof' into your development processes, you can quickly identify processes causing slowdowns and adjust your compile strategies accordingly.

Conclusion

With tools like 'buildprof', developers and decision-makers can not only identify bottlenecks in their compile processes but also implement practical solutions to enhance efficiency and productivity. Ready to optimize your build processes? Let's discuss your project in 15 minutes.

buildprof compile times Bun performance optimization LTO
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