Why is my internet and Wi-Fi super slow lately?

For the past week my Wi-Fi has been very slow. I have a llinksys router and my hp windows vista computer has been slow, my iphone 4s has been slow, i can't even watch videos on my iphone anymore for it takes to long to load videos. My xbox live connection has been slow aswell so i can tell its my Wi-Fi. The other thing is i have comcast internet. I did some of those internet connection tests and i think i did bad. Heres the link for the first one.

i also download the app on my iphone 4s to see its connnection and its definitely the Wi-Fi since my 3g is faster to load videos. Just to get these pictures to download on the computer it took about 5 minutes, normally it takes like 20 seconds. It takes long to open a new broswer aswell.
i finally uploaded this picture which took about 20 mintues.

how can i find out what the problem is or fix it? Is it my router? Should i call my provider which is comcast? I havn't restarted my router or anything like that either.

1. Try restarting both the modem and router (this involved simply unplugging both from a power supply, typically for at least 10 seconds, though I usually go for a minute to be on the safe side).
2. Check your router's setting page and make sure the settings are all correct. Also make sure unauthorized users aren't accessing the network.
3. Contact the service provider, they may have some long-term technical difficulties, be in the process of updating the network, or they might need to send a refresher signal out to your equipment.
4. Try borrowing someone else's router for a day and see how the speeds work out. It's possible your router is just giving out, although usually this manifests itself in other forms (such as disconnecting devices at random).

Have you tried resetting your router? They always come with a reset button somewhere. If you have and still yielding the same results. I'll recommend you call Comcast and have them replace the router cause it has to be a hardware issue on your router's part since the speed has been extremely slow on more than one device.