Optimizing Build and Test Performance
Apply caching, remote execution, and incremental builds to significantly reduce build and test times in large monorepos.
Optimizing Build and Test Performance is a free Git Advanced: Monorepo, Submodules & Workflows lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Git Advanced: Monorepo, Submodules & Workflows learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Faster Builds, Faster Feedback
Welcome! In large monorepos, build and test times can become a major bottleneck. Slow feedback loops hurt developer productivity and can delay releases.
This lesson will show you how to significantly speed up these processes by applying advanced optimization techniques.
The Monorepo Performance Challenge
Why do monorepos often struggle with performance?
- Scale: A single repository can contain hundreds of projects.
- Interdependencies: A small change in one project might affect many others.
- Traditional CI: Often rebuilds and retests everything on every commit, which is highly inefficient.
Introducing Build Caching
Imagine your computer remembering the exact output of a task it just did. That's build caching!
- It stores the results (artifacts) of previous build or test commands.
- If the inputs (code, configurations) haven't changed, it reuses the stored output.
- This avoids redundant work and saves a lot of time.
Local Caching in Action
Monorepo tools like Nx and Turborepo implement local caching automatically. When you run a command, they check a local cache first.
If a cached result exists for the exact inputs, it's retrieved instantly instead of re-running the task.
# First run (may be slow)
npm install
nx build my-app
# Second run (instant, cached)
nx build my-appScaling with Remote Caching
Local caching is great for individual developers, but teams need more. Remote caching shares these cached build artifacts across everyone!
- If a project was built or tested by a teammate or CI, you can download the cached result.
- This means fewer builds from scratch for the entire team and faster CI/CD pipelines.
Incremental Builds: Affected Commands
Why rebuild your entire frontend application if you only changed a backend API? This is where incremental builds come in.
Also known as "affected" commands, they identify and process only the projects that have been impacted by your recent code changes.
How Incremental Builds Work
Monorepo tools create a dependency graph – a map of how all your projects connect.
When you make a change, the tool uses this graph to intelligently determine:
- Which projects were directly modified.
- Which other projects depend on the modified ones.
Only these "affected" projects are then built or tested.
# Run tests only for projects affected by recent changes
nx affected:test
# Build only affected libraries
turborepo run build --filter="[HEAD^...]"Distributing Work: Remote Execution
Even with caching and incremental builds, some tasks are just computationally intensive. Remote execution helps by distributing parts of a build or test command across multiple machines.
This turns a single, long-running task into many smaller, parallel tasks that complete much faster.
Benefits of Remote Execution
Remote execution significantly boosts performance by:
- Parallelization: Running many tasks simultaneously.
- Resource Scaling: Leveraging cloud resources or dedicated build farms.
- Faster Feedback: Getting build and test results back much quicker.
It's especially powerful for large test suites and complex compilation steps.
Check Your Understanding
Which technique focuses on reusing the outputs of previous tasks to avoid redundant work, assuming the inputs haven't changed?
Recap: Optimize Your Monorepo!
You've learned powerful strategies to optimize build and test performance in monorepos:
- Build Caching: Store and reuse results of past tasks, both locally and remotely.
- Incremental Builds: Use dependency graphs to only process projects affected by changes.
- Remote Execution: Distribute heavy workloads across multiple machines for parallel processing.
Mastering these techniques is essential for maintaining developer productivity in any growing monorepo.
Frequently asked questions
Is the “Optimizing Build and Test Performance” lesson free?
Yes — the full text of “Optimizing Build and Test Performance” is free to read here on the web, and the Git Advanced: Monorepo, Submodules & Workflows course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Git Advanced: Monorepo, Submodules & Workflows course, upgrade to CoddyKit PRO.
What will I learn in “Optimizing Build and Test Performance”?
Apply caching, remote execution, and incremental builds to significantly reduce build and test times in large monorepos. You practise Git Advanced: Monorepo, Submodules & Workflows with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Git Advanced: Monorepo, Submodules & Workflows?
No prior experience is required. Git Advanced: Monorepo, Submodules & Workflows on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Optimizing Build and Test Performance” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Git Advanced: Monorepo, Submodules & Workflows lesson?
Yes. Every Git Advanced: Monorepo, Submodules & Workflows lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Code Ownership and Access Control
- Optimizing Build and Test Performance
- Monorepo Migration Strategies
- Dependency Management and Versioning in Monorepos