For me, from undisputed No 1 with 60% share, SS slipped to No 5 after 4 months of going downhill. And, while I don't upload much, I do it on a pretty regular basis. But, the more I upload, the slower SS becomes...Go figure.
Actually, a pretty dramatic slowdown on SS happened about 2 months ago, it was like hitting the wall, and it is only getting worse. Well, at least the other sites perform better and better all the time.