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.
After realizing that I don't care about a light DA trigger pull, I changed the 10-lb hammer spring out for a 13-lb spring (the blue one from CGW).
Now the Shadow Line Compact recoils about the same as a Shadow 2 Compact.
This is after trying all of the much heavier springs from Wolff, none of which seemed to make a noticeable difference. Also, it was cerakoted by Vulcan Machine after they milled it for a red dot.
The hammer spring may indeed make a significant difference. It is noticeable while manually cycling the slide with the hammer dropped. The heavier slide of the S2C may give it a SLIGHT edge in sight movement, but my original irritation has been resolved.
I wonder if using a heavy hammer spring in my CZ85 is the reason I can't tell a difference when I change the recoil spring in it. They all eject the brass to about the same distance.