What’s New in ViteLand: September 2025 Recap

Welcome to another edition of What’s new in ViteLand! Every month, we recap the project updates for Vite, Vitest, Oxc, Rolldown and what’s happening in our community.

Rolldown gets up to 45% faster, and also smaller! ​

Rolldown is the fastest JavaScript bundler, but that does not stop us from striving for even better performance. In the last month, three significant improvements were made!

1. Re-implemented the file metadata retrieval function for Windows. Rust's default standard library runs at suboptimal speed on Windows, and since Rolldown processes large numbers of files during bundling, the new retrieval function improved performance 10-30% for Rolldown builds on Windows.
2. Optimized multi-threaded I/O operations specifically for macOS. Counterintuitively, a higher number of threads opening files on a multi-core macOS system causes a performance degradation instead of expected improvements. In turn, we reduced the number of threads to four, which resulted in 10-45% faster bundling on macOS.
3. Improved source map ignore list. Building with source maps enabled is now 20-30% faster because of reduced Rust-to-JS function calls.

These performance improvements translate directly into faster build times and a smoother development workflow for Rolldown and Oxc users.

Further, the Rolldown team worked on reducing Rolldown's binary size. It was possible to shave off 200KB due to a new way of integrating Oxc into Rolldown. Instead of depending on the @oxc/runtime package directly, the helpers from the package will now be embedded directly into the Rolldown binary during compilation.

Project Updates ​

Vite ​

• Ready to create Rolldown-based Vite apps easily? Vite's create-vite wizard has a Rolldown option now!

Vitest ​

• Using the browser mode for your tests but want to debug them? You can! The Vitest VS Code extension now supports debugging browser tests while being in the browser mode.
• Another improvement for the browser mode: In the next version, it will support playwright's trace viewer natively by passing down a flag.

Rolldown ​

• The team worked on more optimizations, including support for the /* @__NO_SIDE_EFFECTS__ */ annotation across chunks, enhanced tree-shaking across module boundaries and a more efficient dead code elimination.

Oxc ​

• Oxlint is becoming faster and faster! Oxc core team member Cam McHenry submitted two PRs which improve linting speed in real-world codebases by 5-50%.
• Mentioning every performance improvement for Oxc would be too long for this recap post. So, we've compiled a list of all the performance-related PRs, grouped by topic and performance gains.
• Oxlint now supports the popular preserve-caught-error rule, and provides an auto-fix for it!
• Boshen tackled and resolved a nasty memory leak issue with Oxlint when using the import plugin.
• Oxlint can be used within various setups. For all Next.js users, there is an official Oxlint example now!
• The technical preview for Oxlint's custom JavaScript plugins will be released in the next week. Stay tuned! A sneak peek can be found in the tweet below.

Upcoming Events ​

Want to catch talks and presentations from VoidZero team members? Then take a look at the following events where they will be sharing insights and giving talks:

• Oct 2: JetBrains JavaScript Day. Want to know more about faster builds with fewer headaches? Then join Alex's talk.
• Oct 9–10: ViteConf 2025. The first in-person ViteConf with talks from many of the VoidZero team!
• Oct 14–16: JSConf North America. Evan shares insights on overcoming challenges in building faster JavaScript tooling.
• Oct 25: VueFes Japan. Evan gives the event's keynote, Hiroshi prepared a deep dive into Vitest, and Yuji shares his OSS journey with Oxc.
• Nov 20: JSNation. Meet Alex remotely to catch the news about Rolldown and Oxc.
• Nov 28: React Advanced London. Wondering what our tooling has to offer as a React developer? Time to find out in Alex's remote talk!
• Missed SquiggleConf this year? Check out Alex's talk about Rolldown.

From the Community ​

• Evan appeared on the SyntaxFM podcast to discuss modern JavaScript tooling.
• And that's not all! The VoidZero CEO also gave an interview to The New Stack about how Vite became the backbone of modern frontend frameworks.
• Alexander Lichter joined PodRocket for an episode to discuss the latest developments at VoidZero and explains why Rolldown is not just a rustified Rollup.
• Nuno Maduro from Laravel took the time and did both: He interviewed Evan and tried Oxlint live on stream. Don't miss the fun!
• Alexander Lichter demonstrated how Nuxt and rolldown-vite lead to significantly faster builds. The same works for many other (meta) frameworks as well!
• Framer announced their rollout of Rolldown in their build pipeline for all users.
• The Deno team did not only announce the beta of Fresh 2.0, but also that their framework now has a Vite plugin.
• Why using Vitest? According to Artem Zakharchenko, one of the key reasons is Vitest's incredible set of defaults.
• Christophe Rosset shared comprehensive notes from his deep-dive into Rolldown and Oxc internals, providing insights for everyone who wants to understand how the tools work under the hood.
• The Qwik team replaced Rollup with Rolldown for their browser playground, achieving 4x faster performance compared to their previous setup.
• Christoph Nakazawa gave a talk on "Building Scalable Applications", mentioning Vitest, Oxc, tsdown, and Rolldown.
• The popular date library date-fns switched to Oxlint, with author Sasha Koss explaining the reasoning behind the switch.
• Cherry Studio, an open source desktop multi-LLM client, adopted Oxlint in their development workflow for fast linting.
• Developer tools need to work well for Devs and for AI. Good news that some developers noticed that Oxlint works better for AI agents than other tools.
• Vite's official React Server Component plugin scores 100% on Krasimir Tsonev's RSC features support test.
• React Router provides a new Vite plugin to add RSC support for their framework mode.