Build Performance Benchmarks

hx includes a native build mode that bypasses Cabal for simple projects, compiling directly with GHC. This results in significantly faster build times for projects without complex build requirements.

Test Environment

Test project: Simple 3-module executable with Main.hs, Lib.hs, and Utils.hs. Single dependency on base.

Native vs Cabal Build Performance

Cold Build (Clean)

A fresh build after removing all build artifacts (.hx/, dist-newstyle/).

Incremental Build (No Changes)

Subsequent build with no source file modifications.

Why Native Builds Are Faster

Native builds skip Cabal’s build orchestration entirely:

1. Direct GHC invocation — hx constructs the module graph and calls GHC directly
2. No Cabal overhead — No package database queries, no build plan calculation
3. Aggressive caching — Fingerprint-based caching with minimal I/O
4. Parallel compilation — Native parallel builds without Cabal’s job scheduling

When to Use Native Builds

Native builds work best for:

• Single-package projects
• Projects with only base dependencies (or no dependencies)
• Quick iteration during development
• CI pipelines where speed matters

For complex projects with many dependencies, hx falls back to Cabal-based builds which provide full dependency resolution and build planning.

Preprocessor Performance

Preprocessors add minimal overhead to native builds:

Reproducing These Benchmarks

You can reproduce these benchmarks on your own machine:

# Create test project
mkdir /tmp/hx-bench && cd /tmp/hx-bench

cat > hx.toml << 'EOF'
[project]
name = "hx-bench"

[toolchain]
ghc = "9.8.2"
EOF

cat > hx-bench.cabal << 'EOF'
cabal-version: 3.0
name: hx-bench
version: 0.1.0.0
build-type: Simple

executable hx-bench
    main-is: Main.hs
    other-modules: Lib, Utils
    hs-source-dirs: src
    default-language: GHC2021
    build-depends: base
EOF

mkdir src
echo 'module Main where; import Lib; import Utils; main = putStrLn (format greeting)' > src/Main.hs
echo 'module Lib (greeting) where; greeting = "Hello"' > src/Lib.hs
echo 'module Utils (format) where; format s = ">>> " ++ s ++ " <<<"' > src/Utils.hs

# Benchmark native build (cold)
rm -rf .hx dist-newstyle
time hx build --native

# Benchmark cabal build (cold)
rm -rf .hx dist-newstyle
time hx build

# Benchmark incremental (run again without changes)
time hx build --native
time hx build

Historical Results

Methodology

• Cold builds are measured after completely removing .hx/ and dist-newstyle/ directories
• Incremental builds are measured on subsequent runs with no source changes
• Times are wall-clock time from time command
• Each measurement is the median of 3 runs
• Benchmarks run on a quiet system with minimal background processes