--- title: "Flipping Responsibility for Jobs in SpiderMonkey" url: https://daily.dev/posts/flipping-responsibility-for-jobs-in-spidermonkey-wtgncug5v source_url: https://spidermonkey.dev/blog/2026/01/15/job-responsibility.html type: article source: "SpiderMonkey" published: 2026-01-16T17:19:14.822Z updated: 2026-01-16T17:19:34.527Z tags: ["javascript", "performance", "firefox"] reading_time: 5 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Flipping Responsibility for Jobs in SpiderMonkey **[SpiderMonkey](https://daily.dev/sources/spidermonkey)** · 5 min read · 0 upvotes · 0 comments ## Summary SpiderMonkey is changing how Promise jobs (microtasks) are handled to improve performance. The job type is becoming opaque, storage responsibility is moving from embedders to the engine, and the interface for running jobs is changing. These changes allow reusing existing objects instead of allocating new ones for each job, resulting in up to 45% improvement on Promise-heavy benchmarks in Firefox. Embedders using custom job queues will need to update their code, though the changes are mostly mechanical. The work aims to be stabilized by Firefox 153 ESR. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Servo aims to empower developers with a lightweight, high-performance alternative for embedding web technologies in applications.](https://daily.dev/posts/servo-aims-to-empower-developers-with-a-lightweight-high-performance-alternative-for-embedding-web--lh12ugdgc) · Lobsters · 0 upvotes · 0 comments --- Tags: [#javascript](https://daily.dev/tags/javascript), [#performance](https://daily.dev/tags/performance), [#firefox](https://daily.dev/tags/firefox) [View this post on daily.dev](https://daily.dev/posts/flipping-responsibility-for-jobs-in-spidermonkey-wtgncug5v)