Korn Shell, an actively developed free implementation of the Korn Shell programming language and a successor to the Public Domain Korn Shell (pdksh).
Ranked in these QuestionsQuestion Ranking
Pro Very fast
mksh is very light on resources it needs to use and as a result it's quite fast. It also gets better results consistently than other alternatives when comparing benchmarks.
Con Development is pretty slow
Mksh is part of MirBSD which is barely even being developed anymore nowadays.