I'm not sure how much of that is due to the stiffness of the spring or rather due to the fact that the slide is small and hard to grab.
Probably has to do with the springs. My BHP was pretty stiff when I took it home but now it's a little easier now after I've shot it more. The BHP has a 32lbs mainspring and a plenty big enough slide. I never found the CZ75 slide to be small, just "not big." I also found it pretty easy to use, no complaints.