I waste gripping energy by instinctively pressing my grip on the slide downward toward the frame in hopes of preventing any slippage while racking the slide. I guess my brain thinks I can make up for the lack of what for me is the traditional amount of gripping area on a slide the same way I'd press downward on a screwdriver to keep it from slipping in the head of a Phillips head screw.

If one uses the Massad Ayoob approach of griping the pistol while holding the slide stationary, then pushing the frame forward to rack a round into the chamber, this works quite well.  Ayoob has taught this method for decades to make it easier for women who find it difficult to otherwise rack the slide of a semi-auto pistol.

I still do something like that when encountering a semi auto with an extremely heavy recoil spring, but I put both hands to work to make it even easier. I'm a right-handed shooter so I grip the slide with my whole left hand: palm and thumb against the left side of the slide and four fingers against the right side. I make sure my whole hand stays well behind the muzzle and my fingers are carefully away from the ejection port. If I had smaller hands I would grip the slide behind the ejection port. My right hand just takes a shooting grip on the frame. Then I push the frame "forward" to my left while shoving the slide to my right at the same time. I hold the gun about a foot from my chest while doing this so the muzzle never covers my left arm or elbow like it would if you held the frame and slide tight against your body.