On Bittorrent why are my video downloads taking so long?

I downloaded Bittorrent and started torrenting a couple days ago. It was fast when I first started it. Downloaded SPN season 3 in roughly 3 hours and it was 5.4 GB. I downloaded some other files relatively quickly and a couple days later I'm trying to download season 4 which is 7.5 GB. But it's been 3 hours with only 30% progress. It's only 2 GB bigger it shouldn't take this long.
This isn't all either.
I tried downloading ONE episode of an anime that was a 300 MB file and it took 2 hours. What's going on? Why is it slowing down?
I've torrented probably only 8 things so far. Are they somehow effecting the download speed? Should i remove them from the bittorrent list of things i've torrented?