@noby already nailed it with his post explaining why an increased core count will not scale well (actually very bad) with realtime audio performance. In most real-world song projects, four cores are the most renoise can use in a meaningful way.
From my experience and comparisons the most capable CPU for renoise (and RT audio in general) would be Intel’s 12th gen (alder lake) and/or it’s soon to be released 13th gen (raptor lake) successor.
As i own a ryzen 3600 in my ITX build and a 12900K in my main system, i posted a comparison in the benchmark thread:
(click the arrow button to expand the preview, or it will look like a mess)
In conclusion, a 12900K would be more than twice as fast as your current CPU.