Starting Charging issue

[rayray3009]

im having a charging and i think related starting issue with our 01 3.0 x5.
at idle the battery looses charge. new battery and new alternator. the car has always cranked slow but i noticed the cable on the cowl (when you jump the car) is very hot and if you jusp the dead battery atunder the hood the car cranks very fast. much fast then with even the fully charged battery. my question is could a bad/crusty cable fronm the starter to the alternator be the cause if my slow starting and weak charging? replace both cable to the starter and maybe a new starter since its almost winter and i dont want to do it in the cold.
thanks for any suggestions
ray