--- title: Follow up: resize + assign is often faster than reserve... description: A follow-up benchmarking study comparing two strategies for populating std::vector in C++: resize+assign vs reserve+emplace_back. Using GCC 13.2, resize+assign... canonical: https://daily.dev/posts/follow-up-resize-assign-is-often-faster-than-reserve-emplace-back-for-vector-nusmzcdfu twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Follow up: resize + assign is often faster than reserve + emplace_back for vector | daily.dev og:description: A follow-up benchmarking study comparing two strategies for populating std::vector in C++: resize+assign vs reserve+emplace_back. Using GCC 13.2, resize+assign... og:url: https://daily.dev/posts/follow-up-resize-assign-is-often-faster-than-reserve-emplace-back-for-vector-nusmzcdfu og:image: https://api.daily.dev/og/posts/NUSMzcdFU.png og:image:alt: Follow up: resize + assign is often faster than reserve + emplace_back for vector 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. # Follow up: resize + assign is often faster than reserve + emplace_back for vector **[Meeting C\+\+](https://daily.dev/sources/meetingcpp)** · 2 min read · 1 upvotes · 0 comments ## Summary A follow-up benchmarking study comparing two strategies for populating std::vector in C++: resize+assign vs reserve+emplace_back. Using GCC 13.2, resize+assign is consistently faster — up to 1.9x for size_t and 1.6x for a struct of four size_t values. With Clang+libc++, similar gains appear, with up to 2.1x speedup for size_t. The advantage persists even in growing-vector scenarios for smaller data types, though it diminishes for larger structs. The conclusion is that resize+assign is a viable optimization strategy worth testing in code that fills vectors in bulk. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Is resize \+ assign faster then reserve \+ emplace\_back for vector?](https://daily.dev/posts/is-resize-assign-faster-then-reserve-emplace-back-for-vector--af1k8eqai) · Meeting C\+\+ · 3 upvotes · 0 comments - [C\+\+26: std::inplace\_vector](https://daily.dev/posts/c-26-std-inplace-vector-9a9stjxez) · Sandor Dargo · 2 upvotes · 0 comments - [Implementing vector](https://daily.dev/posts/implementing-vector-b9b7cs263) · C\+\+ · 4 upvotes · 0 comments - [Part 1: std::inplace\_vector — The Fixed-Capacity Vector Finally Comes to C\+\+26](https://daily.dev/posts/part-1-std-inplace-vector-the-fixed-capacity-vector-finally-comes-to-c-26-obybukog4) · Towards Dev · 0 upvotes · 0 comments - [Does bulk memmove speed up std::remove\_if? \(No.\)](https://daily.dev/posts/does-bulk-memmove-speed-up-std-remove-if-no--rzbos9ewk) · Arthur O'Dwyer · 0 upvotes · 0 comments --- Tags: [#c++](https://daily.dev/tags/c++), [#performance](https://daily.dev/tags/performance) [View this post on daily.dev](https://daily.dev/posts/follow-up-resize-assign-is-often-faster-than-reserve-emplace-back-for-vector-nusmzcdfu) ```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":"Follow up: resize + assign is often faster than reserve + emplace_back for vector","url":"https://daily.dev/posts/follow-up-resize-assign-is-often-faster-than-reserve-emplace-back-for-vector-nusmzcdfu","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/follow-up-resize-assign-is-often-faster-than-reserve-emplace-back-for-vector-nusmzcdfu"},"datePublished":"2026-03-05T14:43:40.058Z","dateModified":"2026-03-15T05:58:37.686Z","description":"A follow-up benchmarking study comparing two strategies for populating std::vector in C++: resize+assign vs reserve+emplace_back. 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