Yes, it does. Not all CPU cores are created equal. Performance depends on microarchitecture, cache size, memory bandwidth and latency, clock speed, hardware acceleration of specific features, and hyper-threading capabilities, to name a few.

Take the Xeon E5-2403[1] and the Xeon E5-2637 v4[2]. Both are quad-core Xeons, but they differ by pretty much everything except core count.

Here's a comparison of their performance: http://cpubenchmark.net/compare.php?cmp%5B%5D=1827&cmp%5B%5D....

Granted, this is an artificial benchmarks, but the results speak for themselves. In this case, the Xeon E5-2637 v4 is almost three times faster than its little brother, the Xeon E5-2403.

Quantifying CPU performance by number of cores is disingenuous at best, and dishonest at worst.

[1]: http://ark.intel.com/products/64615/Intel-Xeon-Processor-E5-...

[2]: http://ark.intel.com/products/92983/Intel-Xeon-Processor-E5-...

Yes! Running applications that can't cope with NUMA means you need to know what model of CPU, and especially know whether your N-cores are on the same socket or not.