If I had the choice, I would rather that the recoil spring be STRONGER than not.
For one, you KNOW the next round is going to get hit hard enough to cycle. Even with hollowpoints.
Two, it will reduce some of the felt recoil making the second and third shots more accurate (and more comfortable).
My FNP-40 seems pretty normal to me as far as retracting the slide goes. The only other pistol that I have to compare it to has Wolf 22lb recoil springs installed so its not a fair comparison.
It could simply be the difference in the total number of rounds through them both as well.