--- title: Careful with Pair-of-Registers instructions on Apple... description: An optimization introduced in the .NET 9.0 runtime that combines two loads into a single load may cause performance regression on Apple hardware. The ldp... canonical: https://daily.dev/posts/careful-with-pair-of-registers-instructions-on-apple-silicon-daniel-lemire-s-blog-u1egsslav twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Careful with Pair-of-Registers instructions on Apple Silicon – Daniel Lemire's blog | daily.dev og:description: An optimization introduced in the .NET 9.0 runtime that combines two loads into a single load may cause performance regression on Apple hardware. The ldp... og:url: https://daily.dev/posts/careful-with-pair-of-registers-instructions-on-apple-silicon-daniel-lemire-s-blog-u1egsslav og:image: https://api.daily.dev/og/posts/u1Egsslav.png og:image:alt: Careful with Pair-of-Registers instructions on Apple Silicon – Daniel Lemire's blog og:image:width: 1200 og:image:height: 630 og:locale: en --- [Daniel Lemire](https://daily.dev/sources/lemire) [Read post](https://api.daily.dev/r/u1Egsslav) # [Careful with Pair-of-Registers instructions on Apple Silicon – Daniel Lemire's blog](https://api.daily.dev/r/u1Egsslav "Go to post") An optimization introduced in the .NET 9.0 runtime that combines two loads into a single load may cause performance regression on Apple hardware. The ldp instruction, which loads two consecutive values from memory into two registers simultaneously, may have a penalty on Apple silicon when loading data from recently written memory. [#assembly](/tags/assembly "Check all #assembly posts")[#c](/tags/c "Check all #c posts")[#performance](/tags/performance "Check all #performance posts") Apr 29, 2024•2m read time•From [lemire.me](https://api.daily.dev/r/u1Egsslav "lemire.me") [](https://api.daily.dev/r/u1Egsslav "Go to post") 53 Impressions Comment Bookmark Copy Share your thoughtsPost [](https://daily.dev/sources/lemire) [Daniel Lemire](https://daily.dev/sources/lemire "https://daily.dev/sources/lemire") Authored by Daniel Lemire, a computer science professor and researcher, this blog covers a wide rang... Read more 21 Followers • 127 Upvotes #### Would you recommend this post? 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