# How to Speed Up Brave Compilation Cycles with Incremental Builds

> Slash Brave browser compilation times drastically with component builds and compiler caching. Learn how to configure is_component_build = true and use sccache for faster builds.

- Repository: [Brave Software/brave-browser](https://github.com/brave/brave-browser)
- Tags: performance
- Published: 2026-02-16

---

**Enable component builds and compiler caching to reduce Brave compilation time from hours to minutes by configuring `is_component_build = true` and using `sccache` with persistent GN output directories.**

Brave browser is built on top of Chromium and uses the GN + Ninja build toolchain. By default, running `npm run build` performs a full compilation that regenerates GN files and recompiles all source files. This article explains how to speed up Brave compilation cycles with incremental builds using component build configuration, compiler caching, and persistent output directories.

## Understanding Brave's Build Architecture

Brave relies on the same build system as Chromium: **GN** (Generate Ninja) for meta-build configuration and **Ninja** for executing the actual compile and link steps. When you run `npm run build`, the script invokes `gn gen` followed by `ninja -C out/Default`.

According to the repository's [`README.md`](https://github.com/brave/brave-browser/blob/main/README.md) at lines 78-80, the standard workflow generates a persistent GN output directory that Ninja can reuse across subsequent builds. The build graph stored in `out/Default` tracks file timestamps and dependencies, allowing Ninja to skip compilation for targets whose inputs have not changed.

## Configure Component Builds for Faster Linking

The most effective way to speed up incremental compilation is to enable **component builds**. By setting `is_component_build = true` in your GN arguments, you instruct Chromium to build each library as a shared object (`.so` or `.dll`) instead of a monolithic static binary.

This architectural change reduces link times dramatically because:
- A change in one source file triggers recompilation only of the specific shared library containing it
- The final linking step becomes a thin operation that binds pre-built shared objects
- Memory pressure during linking decreases, preventing swapping on resource-constrained machines

To enable this, you must configure the GN args file located at `out/Default/args.gn`.

## Enable Compiler Caching with sccache

Even with component builds, recompiling unchanged source files wastes time. The repository's `.gitignore` file at line 28 explicitly ignores `.sccache`, indicating that the Brave team expects developers to use **sccache** (or `ccache`) for compiler caching.

Sccache stores compiled object files keyed by a hash of the source content and compiler flags. When the same compilation unit is requested again, sccache returns the cached object instantly, bypassing the compiler entirely.

Configure your environment before building:

```bash

# Install sccache

brew install sccache               # macOS

# or: cargo install sccache        # If you have Rust toolchain

# Configure environment variables

export RUSTC_WRAPPER=$(which sccache)   # For Rust components in Brave

export CCACHE_WRAPPER=$(which sccache)  # For C/C++ compilation

export SCCACHE_DIR=$HOME/.sccache       # Cache location (ignored by .gitignore)

export SCCACHE_CACHE_SIZE="50G"         # Adjust based on available disk space

```

With these variables set, Brave's build scripts automatically invoke sccache when calling `clang` or `rustc`.

## Essential GN Arguments for Incremental Builds

Create or edit `out/Default/args.gn` with the following configuration to optimize for incremental compilation speed:

```text
is_component_build = true
is_debug = false               # Component builds default to Debug; set false for Release speed

enable_nacl = false            # Disable Native Client to reduce build targets

use_lld = true                 # Use LLVM's fast LLD linker instead of Gold

symbol_level = 0               # Disable DWARF debug symbols for faster linking

use_custom_libcxx = false      # Use system libc++ where possible

```

These settings work together: `is_component_build` minimizes relinking, `use_lld` accelerates the linking that remains, and `symbol_level = 0` eliminates the overhead of generating debug information.

## Step-by-Step Incremental Build Workflow

Follow this workflow to maintain fast compilation cycles:

1. **Initialize the repository** (one-time setup):
   ```bash
   npm run init
   ```

2. **Generate the build configuration**:
   ```bash
   gn gen out/Default
   # This creates out/Default/args.gn if it doesn't exist

   ```

3. **Configure GN args** as shown in the previous section.

4. **Run the initial build**:
   ```bash
   npm run build
   # Equivalent to: ninja -C out/Default

   ```

5. **Make source changes** and rebuild incrementally:
   ```bash
   # Edit files in src/brave/...

   npm run build
   # Only changed targets recompile due to Ninja's dependency graph

   ```

The `out/Default` directory persists across builds, allowing Ninja to reuse the dependency graph and object files. As noted in the repository's [`README.md`](https://github.com/brave/brave-browser/blob/main/README.md) (lines 79-106), the `npm run build` command simply invokes Ninja on this existing output folder.

## Why Incremental Builds Work

Understanding the mechanics helps you troubleshoot slow builds:

**Ninja's dependency graph** stores timestamps for every output file in `out/Default`. When you re-run `ninja -C out/Default`, it compares source file mtimes against the build log. Only targets with stale dependencies get rebuilt. This graph persists as long as you don't delete the `out/Default` directory.

**Component builds** split the monolithic Chromium binary into shared libraries. In a static build, changing one source file requires relinking the entire browser binary—a multi-minute operation. With `is_component_build = true`, only the specific `.so` file containing your change needs relinking, reducing link time from minutes to seconds.

**Sccache hashing** bypasses compilation entirely for unchanged files. Unlike timestamp-based systems, sccache computes a hash of the preprocessor output and compiler flags. If you've built a file before—even in a different build directory or after a `git clean`—sccache retrieves the cached object instantly. This is particularly effective when switching branches or after running `ninja -t clean`.

## Summary

- **Enable component builds** by setting `is_component_build = true` in `out/Default/args.gn` to minimize relinking time.
- **Use sccache** to cache compiled objects across builds, configured via environment variables and ignored by the repository's `.gitignore`.
- **Preserve the `out/Default` directory** between builds so Ninja can reuse its dependency graph and skip unchanged targets.
- **Optimize linker settings** with `use_lld = true` and `symbol_level = 0` to reduce linking overhead.
- **Run `npm run build`** for incremental compiles; it invokes Ninja on the persistent output directory without regenerating the full build graph.

## Frequently Asked Questions

### What is the difference between a component build and a static build in Brave?

A **component build** compiles Brave's libraries as separate shared objects (`.so` or `.dll` files) rather than linking everything into a single static binary. When you modify source code in a component build, only the specific shared library containing that code needs recompilation and relinking. In a **static build**, even a single line change requires relinking the entire monolithic browser binary, which can take 10-30 minutes depending on your hardware.

### How do I clean the build without losing the incremental cache?

To remove compiled objects while preserving the Ninja dependency graph for incremental builds, run `ninja -C out/Default -t clean`. This deletes the `.o` files and executables but keeps the `build.ninja` and `.ninja_log` files intact. If you are using **sccache**, the compiler cache persists independently in `$HOME/.sccache` (or your configured `SCCACHE_DIR`) and survives even a `git clean` or repository deletion.

### Can I use ccache instead of sccache for Brave compilation?

Yes, you can use **ccache** instead of sccache, though the Brave repository's `.gitignore` specifically references `.sccache` at line 28, indicating sccache is the preferred tool in this ecosystem. To use ccache, set `CC="ccache clang"` and `CXX="ccache clang++"` in your environment, or configure the `CCACHE_WRAPPER` variable. Sccache offers advantages for Brave builds because it handles both C++ and Rust compilation (Brave contains Rust components) and supports cloud storage backends.

### Why does my incremental build still take a long time after switching branches?

When you switch Git branches, the file timestamps change even if the content remains identical, causing Ninja to mark targets as dirty. Additionally, if the branch change modifies header files included by many source files, **sccache** cannot help because the preprocessor output has genuinely changed. To mitigate this, ensure `sccache` is properly configured with a large cache size (`SCCACHE_CACHE_SIZE="50G"`), and consider using `git checkout -f` or `git reset` carefully to minimize unnecessary timestamp updates. If the delay persists, verify that `is_component_build = true` is still set in your `args.gn`, as static linking dominates build times after header changes.