Although externally the Mac Mini seems that it has not been renewed at all, internally we have seen changes in its hardware with the integration of the new generation of Intel processors, a new RAM and other small changes in the arrangement of its components.
All this should indicate a better general performance of the equipment with respect to its previous generation as it would be logical, however this is not fulfilled in its entirety since although the performance in a single processor core is higher compared to the previous one, the performance general multi-core has dropped compared to the Mac mini of late 2012 with quad-core processors with Ivy Bridge architecture, since we remember that these new Mac mini they can only incorporate Haswell dual-core processors.
Unlike single-core performance, multi-core performance has been significantly reduced. The most powerful model in the possible configurations of the Mac Mini compared to the 2012 version, has seen its performance grow by 7%, but on the other hand if we compare the best dual-core of the current Mac mini with the quad-core i7 Ivy Bridge of late 2012, has reduced its performance in comparison, about 70% to 80%.
Perhaps this has to do with the Haswell dual-core processors using by default a connector to associate the motherboard with the processor while quad-core processors of the same Haswell generation use different jacks. This would make Apple have to redesign and adapt two different types of motherboard for different Mac mini models, contrary to what has been happening with previous generations where the entire line used the same motherboard.
This could have been carried out, but surely also production costs would have increased by having two different lines with what the final price would no longer have been so attractive.