--- title: Cache Me Maybe: The Performance Secret Every C++... description: A CppCon 2025 talk by Michelle D'Souza exploring why replacing an unordered_map with a vector yielded a 10x speedup in production. The talk covers CPU cache... canonical: https://daily.dev/posts/cache-me-maybe-the-performance-secret-every-c-developer-needs---michelle-d-souza---cppcon-2025-n5x6fn74a twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Cache Me Maybe: The Performance Secret Every C++ Developer Needs - Michelle D'Souza - CppCon 2025 | daily.dev og:description: A CppCon 2025 talk by Michelle D'Souza exploring why replacing an unordered_map with a vector yielded a 10x speedup in production. The talk covers CPU cache... og:url: https://daily.dev/posts/cache-me-maybe-the-performance-secret-every-c-developer-needs---michelle-d-souza---cppcon-2025-n5x6fn74a og:image: https://api.daily.dev/og/posts/N5X6Fn74a.png og:image:alt: Cache Me Maybe: The Performance Secret Every C++ Developer Needs - Michelle D'Souza - CppCon 2025 og:image:width: 1200 og:image:height: 630 og:locale: 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. # Cache Me Maybe: The Performance Secret Every C++ Developer Needs - Michelle D'Souza - CppCon 2025 **[C\+\+](https://daily.dev/sources/isocpp)** · 45 min read · 0 upvotes · 0 comments ## Summary A CppCon 2025 talk by Michelle D'Souza exploring why replacing an unordered_map with a vector yielded a 10x speedup in production. The talk covers CPU cache fundamentals (cache lines, cache hits/misses, contiguous vs non-contiguous memory), cache-friendly coding patterns like struct member ordering and struct-of-arrays layout, and the pitfalls of microbenchmarking (clock speed ramp lag, out-of-order execution, SMT, core isolation). The talk concludes with an advanced topic: write-combining buffers as a way to bypass the cache for large sequential writes, avoiding the 'read-for-ownership' overhead, with caveats around memory fences and data consistency. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: --- Tags: [#c++](https://daily.dev/tags/c++), [#data-structures](https://daily.dev/tags/data-structures) [View this post on daily.dev](https://daily.dev/posts/cache-me-maybe-the-performance-secret-every-c-developer-needs---michelle-d-souza---cppcon-2025-n5x6fn74a) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Cache Me Maybe: The Performance Secret Every C++ Developer Needs - Michelle D'Souza - CppCon 2025","url":"https://daily.dev/posts/cache-me-maybe-the-performance-secret-every-c-developer-needs---michelle-d-souza---cppcon-2025-n5x6fn74a","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/cache-me-maybe-the-performance-secret-every-c-developer-needs---michelle-d-souza---cppcon-2025-n5x6fn74a"},"datePublished":"2026-04-03T17:28:52.064Z","dateModified":"2026-04-03T17:29:13.299Z","description":"A CppCon 2025 talk by Michelle D'Souza exploring why replacing an unordered_map with a vector yielded a 10x speedup in production. 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