Someone changed one line in the GCC compiler and scored a 12% improvement on modern Intel and AMD chips

One Line x86 Change To GCC Compiler Nets +12% Benchmark Win For Modern Intel/AMD CPUs

Intel software engineer Lili Cui contributed a one-line change to GCC that increases the branch misprediction cost in the generic x86 tuning table. The rationale is that modern CPUs have deeper pipelines, making branch mispredictions more costly, so raising the mispredict scale factor by three helps the compiler avoid pipeline stalls. Benchmarks show a 12.7% gain on Intel Granite Rapids and 12.1% on AMD Zen 5 for the SPEC CPU 2017 544.nab_r NAB test. The change applies to generic x86/x86_64 builds (not -march=native) and has been merged into GCC Git, targeting the GCC 17 stable release.