I made a build visualizer to understand Bun's compile times

The open-source tool buildprof records every process a build command spawns and visualizes them on a timeline, exposing inefficiencies such as poor parallelism, redundant work, dependency downloads, or oversized compiler/linker invocations. Using it, the author reproduced Bun’s Linux CI builds (versions 1.3.14 and 1.4.0) and confirmed the reported >5× speedup, then traced the exact phases—compiler, Full LTO versus Thin LTO linking, and other build steps—to determine which factors accounted for the performance difference.