A processor is the heart of any custom built computer. It is one of the main factors in deciding how fast you want it to go!
When choosing a processor, you need to be looking at the speed which is measured in "GHz". The higher the GHz, the faster it is. Once upon a time, processors used to be single core, they have now advanced into multicore and multithreaded processors. A 4 core or threaded processor is going to be faster than 2 core/threaded processor.
It is also worth noting that we only use the latest processors on the market. We do not sell old out of date processors that no one wants and pretend they are something they are not. This can be a common corner cutting method used by other computer manufacturers.
Finally a 4 cores processor that runs at say 3.4Ghz does not equal 13.6Ghz despite it being a logical process, so if you ever see them advertised like that then the seller has not got a clue!