# Intel microcode update disabled a hardware zero-store optimization on Skylake and Ice Lake

DevFeed: [Intel microcode update disabled a hardware zero-store optimization on Skylake and Ice Lake](<https://devfeed.tech/articles/your-cpu-may-have-slowed-down-on-wednesday-28491.md>)

Original publisher: [Read original article](<https://travisdowns.github.io/blog/2021/06/17/rip-zero-opt.html>)

Author: Travis Downs (travis.downs@gmail.com)

Published: 2021-06-17T00:00:00Z

Content type: article

Language: en

Sources: [Performance Matters](<https://devfeed.tech/sources/performance-matters.md>)

Topics: [cpu](<https://devfeed.tech/topics/cpu.md>), [Optimization](<https://devfeed.tech/topics/optimization.md>), [intel](<https://devfeed.tech/topics/intel.md>), [Benchmark](<https://devfeed.tech/topics/benchmark.md>), [benchmarking](<https://devfeed.tech/topics/benchmarking.md>), [Linux](<https://devfeed.tech/topics/linux.md>), [Security](<https://devfeed.tech/topics/security.md>), [Ubuntu](<https://devfeed.tech/topics/ubuntu.md>)

Tags: [benchmark](<https://devfeed.tech/tags/benchmark.md>), [blog](<https://devfeed.tech/tags/blog.md>), [cpu](<https://devfeed.tech/tags/cpu.md>), [intel](<https://devfeed.tech/tags/intel.md>), [linux](<https://devfeed.tech/tags/linux.md>), [optimization](<https://devfeed.tech/tags/optimization.md>), [performance](<https://devfeed.tech/tags/performance.md>), [security](<https://devfeed.tech/tags/security.md>), [uarch](<https://devfeed.tech/tags/uarch.md>), [ubuntu](<https://devfeed.tech/tags/ubuntu.md>), [x86](<https://devfeed.tech/tags/x86.md>)

## AI overview

An Intel microcode update delivered through Ubuntu 20.04 disabled a hardware zero-store optimization on Skylake and Ice Lake processors, apparently to mitigate CVE-2020-24512. Benchmarks showed slower zero-filling after the update, highlighting that microcode changes can affect CPU performance and benchmark reproducibility.

## Source excerpt

The death of hardware store optimization.