Windows Experience index (removed from more recent versions of Windows) was sadly lacking in actually beaing able to benchmark computers. It only, for instance, evaluated a single core's performance. So the number of cores and actual throughput of a processor was not factored into the results.
A recent i3 might well have a faster single core than an older i5 - but that does not mean that it has yet surpassed the older i5 in total throughput - eventually the gap will grow and ultimately a low-end, recent processor will be faster than the biggest, baddest computer of yesteryear.