Why is Youtube acting so slow?

I never have problems with Youtube, so I don't understand why its acting so slow. I watched a few videos at around noon today and it was working perfectly fine. Now its 10:42 pm (I've been watching videos for about half an hour now.) and its been going so slow and keeps buffering. I had to wait for it to load completely in order for it to play normally and that takes forever, when I can usually watch it right away. I tried watching it on my iPod touch to see if it was just my computer and it did the same thing. So does anyone know why its doing this? Are they just undergoing maintenance or something like that? Please help, thanks!