The overall performance of Intel's range of processors may not have changed much, but what they called an i3, i5 or i7 sure has lately. For example, the popular i7-7700k is most similar in terms of core count, clocks etc to the current i3 chips, and I don't think there was any real equivalent to the current i5 or i7 chips back then. If I remember rightly, the generations prior to that were still seeing actual performance improvements generation-on-generation too.