{
  "id": 6747583,
  "title": "Next.js 16's Turbopack is 2.5x faster, but the bundler is only 4% of your build",
  "url": "https://urgent.news/2026/09/11/next-js-16s-turbopack-is-2-5x-faster-but-the-bundler-is-only-4-of",
  "topic": "tech",
  "section": "Tech",
  "published": "2026-09-11T11:05:00.000Z",
  "source": {
    "name": "Dev.to",
    "slug": "dev-to",
    "url": "https://dev.to/remdore/nextjs-16s-turbopack-is-25x-faster-but-the-bundler-is-only-4-of-your-build-9j9"
  },
  "original_language": "en",
  "account": "Next.js 16 has introduced Turbopack as its default bundler, and the performance boost is significant. In tests with a 60-route app, builds were 2.5 to 5 times faster with Turbopack compared to webpack. However, the bundler itself only accounted for about 4% of the total build time. The majority of the time was spent on other phases, such as TypeScript checking, static generation, and process startup.\n\nOn warm builds, the caching mechanism proved to be the key factor, with Turbopack's persistent cache accelerating the compiling step by 19 times compared to webpack. Despite this dramatic improvement in the compiling phase, the total build time still improved by only 4 times on a warm build. This discrepancy reveals that the bundler's efficiency gains are not directly translated into faster overall build times, especially as the number of static pages increases.\n\nOne surprising finding was the existence of a hidden phase called \"Collecting build traces\" in webpack's build process. This phase took up around 6.6 seconds of the total time without any visible progress indication. Turbopack skips this phase entirely, freeing even more time and contributing to its overall performance advantage. Furthermore, the size of the .next directory was significantly smaller with Turbopack (81 MB vs. 168 MB for webpack), reducing storage and transfer costs when caching build outputs between CI runs.\n\nIn conclusion, while the claim of 2.5 to 5 times faster builds with Turbopack holds true, the true game-changer is the bundler's impact on the overall build time. The significant performance gains in the compiling step are not evenly distributed across the entire build process, and other phases, such as static generation, still consume considerable time. The \"Collecting build traces\" phase in webpack's build process, which is not present in Turbopack, can account for a substantial portion of the build time, making Turbopack's advantage even more pronounced.",
  "summary": "Next.js 16 makes Turbopack the default bundler and puts a number on it: builds 2 to 5 times faster than webpack. I wanted to know whether that holds on something bigger than the starter template, and where the time actually goes, so I built a 60-route app and timed every phase of the build with both bundlers. The headline is true. It is also the least interesting thing I found. The claim…",
  "key_points": [
    "Next.js 16 introduces Turbopack as default bundler, 2.5-5x faster than webpack",
    "Bundler only 4% of total build time, other phases consume majority",
    "Turbopack's caching accelerates compiling step 19x, but total build time only 4x faster"
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}