i686optimized

i686optimized refers to software or build configurations specifically compiled to take advantage of the instruction set extensions and architectural features present in Intel's 6th generation Core processors, codenamed "Skylake," and their compatible successors. The i686 designation historically refers to the Intel 80686 processor, which was the original Pentium Pro. However, in modern software compilation, i686 has evolved to represent a broader class of x86 processors, and "i686optimized" signifies a build targeting a specific set of these modern capabilities.

Compiling software with i686 optimization means that the compiler is instructed to use instructions that are not present in older processors but are available in the target architecture. This can include advanced vector instructions like AVX2 (Advanced Vector Extensions 2) and FMA (Fused Multiply-Add) instructions, as well as other microarchitectural enhancements that can significantly improve performance for certain types of workloads, particularly those involving complex mathematical calculations, multimedia processing, or scientific simulations.

Using i686optimized software on processors that do not support these instructions will result in errors or crashes, as the CPU will encounter instructions it does not recognize. Therefore, such builds are typically made available for users who are aware of their hardware capabilities and are seeking to maximize performance on compatible systems. Many Linux distributions and software projects offer different build variants to cater to a wide range of hardware, allowing users to choose between generic builds compatible with older processors and optimized builds for newer architectures.