Some Meaningful Performance Benefits For Clang + LTO Built Linux Kernels

Over the past few years building the Linux kernel with Clang has matured a lot thanks to upstream improvements to both LLVM/Clang and the Linux kernel. As it's been a while since our last comparison for GCC vs. Clang built kernels on the resulting system performance, our latest year-end 2025 benchmarking is providing a fresh look at the Linux 6.19 upstream Git kernel built under the latest stable GCC 15 and LLVM Clang 21 compilers. Plus with the Clang-built kernel is also the option of the Link-Time Optimized (LTO) kernel for even greater performance.