There is considerable variation in instruction sets across different hardware so you can expect unusual timing differences from one CPU to another. Long ago I remember an AMD processor that did some things really fast against the current Intel CPUs but was slow on may other instructions. Its all silicon acreage that accounts for the difference. I know that Intel over the last 10 years or so have prioritised SSE and AVX over the old integer instructions.
well usual way you choose cpu is to be able to run games and other programs at minimum/recommended stats,long ago I first had AMD athlon with only SSE caps,one step behind intels SSE version,so I got a intel because I wanted latest SSE instructions and ran old legacy landscape raytracing program on both and intel was a disappointment compared to the AMD,probably because program was developed on with good old fpu instructions
one timing I want todo is bitblt,stretchblt,drawiconex and see if there is any difference on milliseconds running on different gpus?