Mob spawns in big caves

The gigantic caves are absolutely impossible to light. I'm not even talking about the hours you would need to spend gathering torches and then placing them in those gigantic caves, but about all the thousands of MOBS you would need to fight. Please, if you don't make those caves smaller, at least reduce the amount of mobs that spawn inside of them. Also, all the caves should be connected to each other, because there are random holes in the ground that aren't connected to anything, but spawn mobs and reduce the efficiency of mob farms above.