Internet/computer speed issues? Choppy youtube, slow loading on Firefox?

[Geoffrey]

I use Firefox, and recently, I've been running into some very bothersome issues with my internet speed.

My internet runs at about 65.0 mbps, so it says, but the loading has been terrible.
Pages load slowly.
On youtube, which is my biggest issue here, videos load just fine, but the playback is choppy, in both video and sound quality. This has never happened until recently.
The loading with youtube videos is mostly okay when youtube is my only tab open, and runs the worst when I have another tab containing Facebook or Tumblr.

I've tried clearing my Cookies, and I ran a CCleaner virus scan.
I also cleared out my documents and saved files, but still my internet is running poorly.

What else can I do?

[simon]

Phone your ISP tell them you will cancel your standing order of somethings not done. Always works.

[Jacob]

Its because of the new windows 8. Everyone who isent running 8 is or will be suffering soon its messed up that they have that much power