The performance of NinjaTrader 8 and MZpack indicators depends on the complexity of your charts and intensity of orderflow of your instrument mainly, but not CPU performance. Note, 1 instrument x 10 instances will create significantly more load than 2 instruments x 5 instances per each.
The minimal is Intel Core i3/4Gb for 3-5 instances of indicators.
The recommended number of cores at least 4. Note, that single-core performance is more important than the number of cores.