Disgaea D2 [BCAS20301]

There is always going to be a single thread that is a bottleneck for the rest, so one out of six cores on your CPU is loaded to its max while the other have a little less to do. A single Kaby Lake core is almost twice as fast as an AMD FX core too (Take note that his laptop CPU likely could turbo higher than 2.5 ghz, maybe up to 3 ghz or so).

Anyway, there is a performance hack/patch for this game, use it: https://www.patreon.com/posts/march-progress-8627774