Not slow, but theyd be typically less agile due to the acrobatics the jedi can do, but they are also a lot harder to actually put down

Really depends on who, vader would win against the average marine, but put him up against someone like mephiston and hes gonna lose. Average vs average though, space marines i think have the edge. Way harder to put down, more experience, and way better in strength and speed, plus the bolters would f**k up a jedi since lightsabers dont do ballistics well