Build Time Optimization Guide

This document outlines the build optimizations applied to the yumlabs project.

Optimizations Applied

1. Cargo Build Profiles (Cargo.toml)

Development Profile (dev)

• opt-level = 0: No optimization for fastest compilation
• codegen-units = 256: Maximum parallelization during compilation
• incremental = true: Incremental compilation enabled (default, but explicit)
• Dependency optimization: All dependencies compiled with -O2 even in dev mode
  • Dependencies are compiled once but used many times, so optimizing them improves runtime without affecting incremental build times

Release Profile (release)

• opt-level = 3: Maximum optimization for best performance
• lto = "thin": Thin Link-Time Optimization for better optimization with reasonable compile time
• codegen-units = 1: Single codegen unit for maximum optimization
• strip = true: Strip debug symbols for smaller binary size
• panic = "abort": Smaller binary and faster panic handling

Fast Release Profile (release-fast)

• New custom profile for quick release testing
• opt-level = 2: Good optimization without the full cost of -O3
• lto = false: No LTO for faster linking
• codegen-units = 16: Parallel compilation for faster builds
• Use with: cargo build --profile release-fast

2. Linker Optimization (.cargo/config.toml)

• rust-lld.exe: Uses LLVM's LLD linker instead of MSVC's default linker
  • 2-5x faster linking on Windows
  • Comes bundled with Rust, no additional installation needed

3. Build Settings

• jobs = 0: Uses all available CPU cores for parallel compilation
• protocol = "sparse": Faster crate index updates (requires Rust 1.68+)
• git-fetch-with-cli = true: Better git performance for dependencies

Expected Performance Improvements

Build Type	Expected Improvement
Initial clean build	10-30% faster
Incremental builds	30-50% faster
Dependency updates	Significantly faster
Linking time	2-5x faster

Usage

Development Builds

cargo build          # Uses optimized dev profile
cargo run            # Fast compilation with optimized dependencies

Release Builds

cargo build --release              # Full optimization (slower build, fastest runtime)
cargo build --profile release-fast # Quick release build for testing

Additional Tips

1. Clean builds when needed: If you encounter issues, run cargo clean and rebuild
2. Dependency caching: First build will be slower as dependencies are optimized, subsequent builds will be much faster
3. Parallel compilation: Ensure you have sufficient RAM (256 codegen units can be memory-intensive)
4. Monitor build times: Use cargo build --timings to analyze build performance

Troubleshooting

If builds are slower

• Reduce codegen-units in dev profile (try 128 or 64 instead of 256)
• Ensure you have enough RAM for parallel compilation

If linker fails

• Remove the linker configuration from .cargo/config.toml
• Fall back to default MSVC linker

If you need debug symbols in release

• Set debug = true in [profile.release]
• Or use cargo build --profile release-fast which can be modified to include debug info

Files Modified

• Cargo.toml: Added build profiles
• .cargo/config.toml: Added linker and build configuration (created new)