Well, 2500k doesn't have AVX2 instructions (for 256-bit width), so integer stuff needs to use 128-bit wide SSE2+. In some [1] cases that can make quite a bit o

Well, 2500k doesn't have AVX2 instructions (for 256-bit width), so integer stuff needs to use 128-bit wide SSE2+. In some [1] cases that can make quite a bit of difference, up to almost 2x. [1]: Real improvement is of course anywhere between none and 2x. A lot of software (most even?) is still not using AVX2 at all. Sorting, memory block operations (strlen, memcpy, etc.) and operations that need to do integer math on big chunks of data can benefit significantly. Some real world code I wrote saw up to ~1.9x improvement on systems with sufficient memory bandwidth.