The Core i5 Retina iMac is slightly faster than the other Core i5 iMacs, and is competitive with the Core i7 iMacs in single-core performance. However, the Core i7 iMacs are up to 20% faster in multi-core performance. These Geekbench results aren't surprising since all of the iMacs use Haswell processors; any performance increase is due to the increase in clock speed.
The site also compared the Retina iMac to the Mac Pro. Notably, the Core i5 Retina iMac is faster at single-core tasks but slower at multi-core tasks.
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