This isn't uncommon in either rougher-machined guns, or really tight guns, including some done by top gunsmiths. It's a bit of a bell-curve that way, with the quality on either end showing that behavior. It's generally related to tight locking-lug lockup and the back of the barrel hood pressing against the breach-face, the friction from the bottom of the firing-pin stop where its radius is in contact with the hammer, and where the disconnector first contacts the bottom of the breach-face on the forward stroke of the slide. Stutters and the slide slowing down are often alleviated with wear and/or really good lubrication in these places.
If you can secure a lightweight grease in NZ, those are 3 spots that benefit a great deal from it being applied to them. TW-25B or cherry balmz are the best I've tried. You want it about the consistency of a lotion, so a #0 grease. You can also cut down a heavier #2 lithium-complex automotive grease by adding oil and stirring really well, to get it down to that consistency. Only thing to watch out for with that is if you're in really cold weather, to use a 0W-something oil, but in most climates you're good-to-go with whatever motor oil you're using in your vehicle. That same grease applied to all your friction surfaces will make it feel like a different gun.