How about the hammer spring? It takes some force to push the slide back over the hammer and compress that hammer spring. Lot's of people seem to like to replace the factory spring with a lightened hammer spring.
Then there's that corner at the rear/bottom of the slide. The sharper the angle the more rearward force it takes to start cocking that hammer. Again, some people have that corner rounded off to make racking the slide easier and/or make it easier for light recoiling ammo to move the slide to the rear. Old 1911 thing (only with the firing pin retaining plate lower rear corner, not the slide.
Good luck with it.