I know this is the oldest problem in the book, but my computer has slowed right down. Especially Youtube.

I have an Dell Inspion laptop running XP.

I ran a speed test and the connection seems ok, so I guess it's something internal.
I have run defragged twice, run CCleaner, AVG, Malwarebytes, and Advanced System Care, and it's still the same.

Can someone please suggest something else ? I'm in pain.