why Hashcat v6.2.6 is slower than v4.1.0 (or 5.1.0)

[NoReply]

Just a hunch, but maybe there is a bug such that it uses the optimized kernel in Versions 4.1.0 and 5.1.0 although it says pure kernel is selected.

You could figure out by feeding it long candidates and check whether you get any rejected candidates.