Maclisp ran quite fast on the PDP-10, even faster than DEC's FORTRAN (for a while, DEC was sufficiently embarrassed they put more effort into it).
High quality Lisps being proprietary during the chaotic '80s through the early-mid '90s was certainly an issue for Maxima, but for the licensed Macsyma (see my other comment on the history) I think that would have been an acceptable part of the cost of goods; too bad Symbolics demanded you by one of their Lisp Machines to run it for too long.
Self-promotion ... yeah, Mathematica wins hands down there ^_^.
High quality Lisps being proprietary during the chaotic '80s through the early-mid '90s was certainly an issue for Maxima, but for the licensed Macsyma (see my other comment on the history) I think that would have been an acceptable part of the cost of goods; too bad Symbolics demanded you by one of their Lisp Machines to run it for too long.
Self-promotion ... yeah, Mathematica wins hands down there ^_^.