cookie-free domain

[gallasfer]

Hi

I have 2 websites:
- WordPress website x hosted at "a" hosting company
- one-page html website y hosted at "b" hosting company

I run a speed performance for website y.
The report tells me " There are 36 components that are not cookie-free" and shows me 34 URL from website x , for example:
http://www.website_x.com/wp-content/uplo...00x179.jpg

How is it possible? What is the issue?
Two diferent hosting companies... how can the tester identified this issue?

Please, help me.
Thank
F.