--- title: Turbocharging V8 with mutable heap numbers · V8 | daily.dev description: The V8 team recently optimized JavaScript's performance, specifically targeting the async-fs benchmark which saw a 2.5x improvement due to changes in how... canonical: https://daily.dev/posts/turbocharging-v8-with-mutable-heap-numbers-v8-aljp7chjk twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Turbocharging V8 with mutable heap numbers · V8 | daily.dev og:description: The V8 team recently optimized JavaScript's performance, specifically targeting the async-fs benchmark which saw a 2.5x improvement due to changes in how... og:url: https://daily.dev/posts/turbocharging-v8-with-mutable-heap-numbers-v8-aljp7chjk og:image: https://api.daily.dev/og/posts/aLjp7Chjk.png og:image:alt: Turbocharging V8 with mutable heap numbers · V8 og:image:width: 1200 og:image:height: 630 og:locale: en --- [V8](https://daily.dev/sources/v8) [Read post](https://api.daily.dev/r/aLjp7Chjk) # [Turbocharging V8 with mutable heap numbers · V8](https://api.daily.dev/r/aLjp7Chjk "Go to post") The V8 team recently optimized JavaScript's performance, specifically targeting the async-fs benchmark which saw a 2.5x improvement due to changes in how Math.random's seed value is handled. They implemented a two-part optimization focusing on slot type tracking and mutable heap numbers to enhance efficiency, avoiding frequent heap allocations and leveraging integer operations. These changes contribute to a significant boost in the overall JetStream2 benchmark score. [#javascript](/tags/javascript "Check all #javascript posts")[#performance](/tags/performance "Check all #performance posts")[#v8](/tags/v8 "Check all #v8 posts") Feb 25, 2025•5m read time•From [v8.dev](https://api.daily.dev/r/aLjp7Chjk "v8.dev") [](https://api.daily.dev/r/aLjp7Chjk "Go to post") Table of contents [The target async-fs and a peculiar Math.random #](https://api.daily.dev/r/aLjp7Chjk?a=the-target-async-fs-and-a-peculiar-math.random "The target async-fs and a peculiar Math.random #")[The bottleneck #](https://api.daily.dev/r/aLjp7Chjk?a=the-bottleneck "The bottleneck #")[The solution #](https://api.daily.dev/r/aLjp7Chjk?a=the-solution "The solution #")[The results #](https://api.daily.dev/r/aLjp7Chjk?a=the-results "The results #") 25 Impressions4 Upvotes Comment Bookmark Copy Share your thoughtsPost [](https://daily.dev/sources/v8) [V8](https://daily.dev/sources/v8 "https://daily.dev/sources/v8") The V8 Blog provides updates, technical deep dives, and insights on V8, Google's open-source JavaScr... 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