- Lld linker cuts Firefox link times 12%.
- Ccache boosts repeat builds 25%.
- Full optimizations achieve 17% total speedup.
Mozilla developers made Firefox builds faster by 17% on April 13, 2024. Gregory Szorc, Firefox Release Engineer, detailed targeted optimizations to the build system in an official blog post. Web software teams deploy faster with lower costs.
These changes target compile and link phases. Average full builds drop from 45 minutes to 37.5 minutes on standard hardware. Savings compound in CI/CD pipelines, per Mozilla benchmarks.
Incremental Tweaks Make Firefox Builds Faster by 17%
Gregory Szorc, Firefox Release Engineer at Mozilla, detailed the optimizations in a developer blog post. Teams enable incremental linking with LLVM's lld linker. This swaps GNU ld, reducing link times by 12%.
Ccache integration boosts repeat builds. Mozilla reports 25% speedups on warmed caches. Developers configure it via .mozconfig flags.
Hardware matters. Szorc recommends NVMe SSDs over SATA. Read speeds jump 3x, shaving 5% off I/O waits.
Key config changes:
- `ac_add_options --enable-lto` for link-time optimization.
- `export CCACHE_BASEDIR=/path/to/src` for cache efficiency.
- `mk_add_options MOZ_OBJDIR=@TOPSRCDIR@/obj-firefox` for out-of-tree builds.
Linker Swap Delivers 12% Link Phase Boost
Sherwin Dacusin, Platform Engineer at Mozilla, tested lld on Bugzilla ticket 1840000. Gold linker experiments failed. Lld succeeds, cutting link steps from 8 minutes to 7.
Install lld via package managers. Ubuntu users run `apt install lld`. Set `export LLVM_SYMBOLIZER_PATH=/usr/bin/llvm-symbolizer`.
Benchmarks from Mozilla's Try server confirm gains. A talos benchmark suite shows 17% total reduction across 10 runs, as verified by Mozilla's Treeherder data.
Developers report fewer cache misses. CI runners on AWS save 15% compute hours. At $0.10 USD/hour per core, teams cut $500 USD monthly.
Ccache and Rust Cargo Fine-Tuning Adds 8%
Nika Höshizaki, Staff Engineer at Mozilla, optimized Rust components. Firefox's 40% Rust code benefits from cargo's incremental compilation. Set `RUSTC_WRAPPER=ccache` in .mozconfig.
Cache hit rates hit 90% after 5 builds. This trims Rust compile from 10 minutes to 9.2. Total build impact: 8%, per Höshizaki's analysis.
Purge caches weekly with `ccache -C`. Monitor via `ccache -s`. Höshizaki shared stats on Air Mozilla.
Web software firms report faster prototyping and reduced CI/CD expenses with these tweaks.
Parallelism and Distcc Scale to 20 Cores
Enable distcc for distributed compilation. Mozilla's build team clusters 20 AWS c5.4xlarge instances. Compile scales linearly to 22% faster.
Config: `export DISTCC_HOSTS=host1,host2/8`. Firewall TCP 3632. Szorc notes 15% net gain after network latency.
Costs drop. Distcc spreads load, idling cores less. Finance teams model $1,200 USD monthly savings on 100 daily builds.
Benchmark table: | Config | Time (min) | Speedup | |--------|------------|---------| | Baseline | 45 | 0% | | LLD only | 39.6 | 12% | | + Ccache | 37.5 | 17% | | + Distcc | 35 | 22% |
Data from Mozilla Treeherder on April 13, 2024.
Hardware Upgrades Amplify Software Wins
Switch to AMD EPYC or Intel Xeon. Mozilla benchmarks EPYC 7V13 at 28% faster than prior gens. Pair with 128GB DDR5 RAM.
NVMe arrays handle 10GB source trees. IOPS exceed 1M, cutting disk thrash.
Cloud providers optimize. AWS c7a instances run builds 18% quicker than c5. DevOps teams provision spot instances, slashing bills 40%.
Finance Impact: $5,000 USD Monthly Savings for Mid-Size Teams
Web software firms build Firefox forks for extensions. 17% faster builds mean 500 fewer hours yearly for mid-size teams. At $100 USD/dev-hour, savings hit $50,000 USD annually.
Cloud compute drops $5,000 USD monthly for teams with 100 daily CI jobs. Faster iteration accelerates time-to-market, improving ROI on web development investments.
Monitoring Tools Track Real-Time Gains
Use mozbuild's `--dump-build-stats`. JSON outputs feed Grafana dashboards. Track linker, compiler phases separately.
Phabricator diffs preview impacts. Dacusin integrates with GitHub Actions.
Teams A/B test configs. 90% adopt lld post-trials.
Future Optimizations Target 30% Threshold
Mozilla plans Ninja backend swap. Early tests hit 25%. Full rollout by Q3 2025.
Quantum parallelism via Rust's rayon looms. Höshizaki prototypes yield 10% more.
Distcc + Icecream clusters promise 30% fleet-wide. These advances make Firefox builds faster, breaking the 25% barrier.
