Bun speed leads monorepo installs but pnpm provides better isolation

Bun speed leads monorepo installs

Bun 1.4 completes a Turborepo monorepo installation containing 2,341 packages in 4.1 seconds. This speed beats pnpm, which requires 21.7 seconds for the same task, and npm, which takes 89.4 seconds. For a small project with 50 dependencies, Bun finishes in 1.41 seconds while pnpm requires 13.49 seconds. When running a large monorepo containing 15 packages and 800 dependencies, Bun completes the installation in 4.8 seconds, whereas npm takes 89.4 seconds and pnpm requires 21.7 seconds. The Bun package manager uses the Zig programming language and a custom HTTP/2 client to drive these speeds. Bun uses a flat node_modules layout similar to npm. This design allows phantom dependencies to exist because it lacks the strict isolation found in other tools. Bun 1.3 and 1.4 also include workspace filtering capabilities that match the performance of pnpm. Bun uses a binary lockfile called bun.lockb to improve performance, although it offers an opt-in YAML version for human readability. Benchmarks on an M3 MacBook Pro show that Bun’s speed advantage grows significantly as the dependency count increases. In high-throughput scenarios, Bun 1.4 delivers 48,243 requests per second, which exceeds the 25,181 requests per second provided by Node.js 26.7.0.

Dependency isolation in monorepos

pnpm 12.1.0 enforces strict dependency isolation through its symlinked node_modules structure. This mechanism prevents a package from accessing any dependency not explicitly listed in its own package.json. In contrast, Bun 1.4 lacks this strictness, meaning a developer might accidentally rely on a transitive dependency. Yarn Berry 4.18.0 approaches isolation differently by using Plug’n’Play to replace the node_modules folder with a .pnp.cjs file. This method enables zero-installs, allowing teams to run projects immediately after cloning without waiting for an installation step. Yarn Berry also uses a constraints system to enforce version consistency across every workspace package. However, many tools that traverse the directory tree struggle with PnP compatibility. pnpm 12.1.0 provides version catalogs for managing shared dependency versions across a monorepo. pnpm also provides improved performance for the --filter command in large workspaces. pnpm supports the workspace:* protocol, which ensures that workspace packages always resolve to the local version. Yarn Berry includes a plugin architecture for extensibility and uses its own JavaScript-based constraints engine.

Storage efficiency and CI pipelines

pnpm saves 50% to 70% of disk space compared to npm by storing package versions once in a global content-addressable store. It uses hard links to connect these packages to individual projects. This approach helps developers managing dozens of projects on one machine. In CI/CD pipelines, pnpm and Bun provide the best performance. Bun’s install speed advantage grows as project size increases. For a 15-package monorepo with 800 dependencies, Bun finishes in 4.8 seconds, while npm takes 89.4 seconds and pnpm requires 21.7 seconds. pnpm 12.1.0 makes --ignore-scripts the default in CI mode to reduce supply chain attack surfaces. pnpm uses a YAML lockfile, which provides a compact format for security audits. The pnpm global store resides in the ~/.pnpm-store directory. All four managers use lockfiles that generate integrity hashes with SHA-512 checksums for every installed package. The pnpm lockfile, pnpm-lock.yaml, remains highly efficient for large-scale projects. You should choose pnpm for large monorepos requiring strict version management and workspace protocols. Does the speed of a single tool outweigh the stability of a more established ecosystem?