Turbopack excessive memory usage (~7GB+) in dev mode compared to Webpack (~3GB)

[2hmad]

When running Next.js in development mode with Turbopack enabled, memory usage grows significantly (up to ~7GB), even with memory limits configured. Switching to Webpack under the same project reduces memory usage drastically (~3GB), suggesting a Turbopack-specific issue.

Environment:

• Next.js: 16.2.3
• Runtime: Node.js (via Bun script)
• OS: WSL (Ubuntu)
• Editor: VS Code Remote
• Project type: large Next.js app (frontend)

Steps to reproduce:

• Run the project with Turbopack bun dev
• Observe memory usage using top
• Wait for initial compilation to finish.

Current behavior

• next-server process grows to ~7GB RAM usage
• High CPU usage during compilation
• Memory remains high even after compilation stabilizes
• Occasionally high I/O wait observed

Trace file:
Download trace file

[yudin-s]

Since this is WSL + VS Code Remote + a large app, I would separate three things before treating it as one Turbopack memory bug:

1. Cold compile peak: memory rises during the first full graph build.
2. Stable idle size: memory after compilation is done and no files change.
3. HMR growth: memory increases after repeated edits and never comes back down.

Those point to different problems.

A useful triage plan:

• make sure the repo lives inside the WSL filesystem, not under /mnt/c/...
• exclude .next, node_modules, generated folders, and large asset folders from VS Code file watching/search
• run the same command with Node instead of Bun once, to remove Bun script/runtime effects from the test
• compare next dev --webpack vs Turbopack from the same clean boot
• capture memory after first compile, after 5 minutes idle, and after 10 repeated HMR edits

The trace file is useful, but the next most valuable data is whether memory is retained while idle or only spikes during compile. A high compile peak may be expected for a very large graph; unbounded growth after HMR edits is much more actionable as a leak.